Here's two suggestions for you. The first is indeed the connection to the Western Express route. This would take you east from SF (includes ferry trip $$) through Sacramento and over to CA 88 to Carson Pass, shortly after which you would turn north on CA 89 on the SC route. This route north would take you around the west side of Lake Tahoe. This route involves a fair bit of climbing, which by the time you reach SF you should be used to.
A second suggestion is, in Ft. Bragg consider take CA 20 east. Ft. Bragg -> Willits -> Ukiah -> Clear Lake -> Williams. Once in the valley you could take CA 45 north, connect to CA 162 to continue east and thence to CA 70. You could then take advantage of the easy grades and the spectacular scenery in the Feather River Canyon, rejoining the Sierra Cascades route at CA 89 north of Quincy to continue north to Greenville and Lake Almanor and beyond.
You better not be worried about climbing. All of CA coast is steeper than most coastal routes in WA or OR. Those states have generally consistent grades around 6% max.. Once in CA you will see that number go up. The CA coast will beat your legs up with its constant up and downs. Once you turn inland you again will see many long climbs as well.
I'm not sure I understand the complaint about the cost of the ACA maps. You certainly could do your own research and perhaps get by without the maps. Seems to me that when you look at the complete cost of the trip, the maps are an incidental cost and cheaper than being lost.
Craig
Santa Rosa, CA