I rode your intended route during the first week of September in 2010. I used that route to connect from Ventura to Bishop, CA, and then I continued across Nevada on Highway 6.
In case future searchers are interested, here is my tale. I encountered very little traffic on your route, so no worries there. Along the coast that summer, it was cool and overcast, and during the Anacortes, WA to LA leg of my tour, I rarely saw the sun. But after leaving the coast in Ventura, CA and turning inland, the temperatures climbed into the 90's. I camped in Ventura at the hiker biker site in McGrath state park, which was a shithole, and adjacent to a site with 30-40 drunken partiers.
To avoid traffic on 33 out of Ventura, I rode on N. Ventura Ave. until I happened upon a bike path (which both parallel 33). I believe the bike path got me close to Ojai. There is a way to avoid Ojai by taking a left on Baldwin Rd, and then continuing north on Rice Rd, which is what I did (it’s a very obvious shortcut when you look at Highway 33 near Ojai on google maps).
I was worried about finding water up in the arid Ventura hills, so my plan was to load up on water at the last possible place. At a local bike shop in Ventura, I learned that there was water at a campground about 1/4 of the way up the climb. After that, I didn't know where I would find water again.
I found the campground, but the water pump had a sign on it declaring the water unfit for drinking, and the pump was locked. Disaster! I spied a ranger station just up the road, so I went in there to ask for assistance. No one was around, and there was a similar sign on their pump, but their pump was unlocked. Even though the sign said that filtering the water wouldn’t be adequate, I had no other choice, so I pulled out my filter and filtered some water into my bottles and one of my supplemental bladders. With a full load of water, I continued on up the climb.
As I climbed higher, it got hotter. About 3 ½-4 hours after leaving Ventura, I reached the summit. I think the elevation was 3,000 feet. The view back down the canyon was beautiful. From the summit, I inexplicably descended only about 500 feet and then the road flattened out. When I stopped to transfer water from the bladders in my panniers to my water bottles, I was attacked by swarms of flies that tried to get in my ears and eyes. The flies would also swarm around my face whenever the road inclined upwards and my speed slowed.
Because of the heat and the long climb out of Ventura, I was depleting my water supply pretty fast, so I looked for water along the road. I did see some water but it wasn’t easily accessible, so I continued on. Then to my horror the road started rising steadily upwards again. Another climb! I eventually summited a pass called Pine Mountain as dusk descended, elevation: over 5,000 feet. The legs of my bibs were layered with sweat rings, like the 3,000 year old redwoods I encountered in Northern California. I was trembling from the effort and partly from fear: I had half a bottle of water left, but I was thirsty, and I had no idea where I would find more water. I choked down half a Cliff bar while I equipped my bike with lights for night riding and put on a wind breaker. I descended slowly because I was shaking from exhaustion, and I didn’t trust my ability to stay upright. Miraculously, at the bottom of the descent there was a fire station. No one was around, but next to the visitor parking lot, there was a grove of trees, a picnic table, and a drinking fountain! I greedily lapped up the cool water and splashed it over my head. I got some food out of my panniers and arranged it on the picnic table for dinner. As I ate, I decided to camp right there, next to the picnic table, under the grove of trees, with the breeze gently chiming the leaves, and the stars shining brightly overhead.
But then some sprinklers came on. Drat! I grabbed my food and ran for the parking lot. My original plan was to continue north on Highway 33, ride to Lake Isabella, and then make my way to Bishop, CA. So I loaded up with water at the fire station and continued north on 33 in the dark. I was so wasted that I immediately started looking for a place to camp. About 5 miles north of the fire station, I found a spot on the west side of the road in a sandy wash. I set up my tent next to a large tree, and then I fell fast asleep. That was the hardest day of riding up to that point on my tour, and I had come west on the Nothern Tier from Whitefish, MT, and crossed over three major mountain ranges.
The next morning when I woke up, I decided it would be prudent to go back to the fire station to fill up on water. Then I retraced my steps and continued north on 33 until I reached a café in Ventucopia, where I stopped for breakfast (but mainly to use the bathroom). The people in the café asked me where I was going, and I told them I was headed to Lake Isabella. My statement was greeted with a look of horror. The people told me that because of the holiday weekend it was way too dangerous to ride a bike up the twisting, mountainous roads to Lake Isabella. They convinced me to turn around, backtrack to the fire station and head east on Lockwood Valley Rd. My new destination was to be Frazier Park, and from there I would make my way to Bishop, CA, skirting the Sierras. The people in the cafe said that the road was pretty flat to Frazier Park, and there would only be light traffic.
So back to the fire station I went for a third visit, where I filled up with water again, and then I turned onto Lockwood Valley Rd (which I don’t think is marked with signage). There wasn’t any traffic on Lockwood Valley Rd., but it sure wasn’t flat. It consisted of an interminable number of short steep rollers, which are momentum killers for a fully loaded touring bike. I don’t know if I was feeling the effects from the previous days hard effort, but with the backtracking already mentally putting me in a hole, the ride through Lockwood Valley turned out to be pure hell. It was hot, and I felt mentally and physically drained. The riding was arduous, and it wasn’t until late in the afternoon that I finally limped into a town just outside of Frazier Park, where I sat outside at a picnic bench and guzzled Gatorade and ate ice cream. I continued onto Frazier Park (which was a down hill coast all the way) where I decided to treat myself to a motel room ($50 on the holiday weekend, next to a small grocery store), so I could take a a badly needed shower and try to recover.
The next day, I continued on to Interstate 5, where I turned south, and as someone else mentioned, there is a frontage road along the right side of the freeway, and then at Gorman the frontage road goes under the freeway and continues south on the other side of the freeway. The frontage road connected me to 138, and then I rode east on 138 all the way to the Sierra Highway(which parallels the Antelope Valley Freeway). I found cafe’s every 15 miles along 138, and I stopped at each one for a large ice cold Dr. Pepper to help me beat the oppressive heat. I was paranoid about running out of water after my ordeal in the Ventura hills, so I lugged along a full load of water, which I never needed.
At the Sierra Highway, I turned north to Rosamond. In Rosamond, I saw a sign for “The Best Bike Shop Ever”, so I stopped and had them take a look at my rear wheel, which plagued me my entire tour with spokes that loosened daily (brand new 40 hole Velocity Dyad with XT hub).
In summary, the riding along that portion of my tour was challenging, it was hot, the roads were generally good, and the traffic was light. I had a great adventure.
Due to some big changes in my summer plans, I'm going to end up doing a shorter, different tour in the american west this summer (Logan, UT to Glacier NP, MT).
I also did that route as part of my tour. Excellent riding. Highly recommeded. I hope you had as good a time as I did.