Hey, Psemler: May can be a great time to start. My wife and I have ridden the Carson City to Davis portion of that route and will do it again this year. The problem you are likely to encounter (aside from whatever weather is moving through) is the likely closure of the Mormon--Immigrant Trail, which connects Hwy 50 to Hwy 88. Last time we crossed (in May) after a heavy winter--LIKE THIS YEAR--and the road was buried in snow. We were traveling east to west (as we will this year), so we just kept dropping down 88 until we could peel off the main route. I think we took Shingle Ridge Rd., if I recall. Regardless, we ended up a good deal south of Folsom but found some nice connecting roads to get us back north.
The problem with going all the way up through Placerville and such and THEN finding your route cut off is then you have to back track or continue along Hwy 50. I've driven this stretch many times. There is no way you'd get me to bike it. Fantastic loads of fast traffic headed into Lake Tahoe, often little to no shoulder. Cyclists have survived it, but OY! Plain misery as far as I can see. Do some careful research before heading out and plan your route accordingly. If you end up riding through the gold country foothills, avoid Hwy 49, which carries the bulk of the north/south traffic. In general, try to avoid the main Sierra crossing on a weekend.
I just checked the map, and I see that from Placerville, you can follow back roads south and then east to pick up Hwy 88 west of the Mormon/Immigrant Trail. This will almost certainly involve some sharp climbs and descents. I don't know about traffic. There has been a ton of development in the gold country over the last decade, so you should be prepared for anything. You could probably get great local info. from a bike shop in Placerville.
Plan on sweating across the Midwest, but you might be okay if you can hit it before July. I crossed east to west in Sept./Oct. and found plenty to perspire about in Kansas. Actually, west Kansas was the toughest part of my tour--boring, long, windy, just-plain-tough.
Best of luck on your tour! You'll love Nevada if you are into big, lonely, wild places. The basin and range country is some of my favorite.
Oh, one more thing: Hwy 50 dropping into Canon City, Colorado, might be pretty crazy with all the spring rafting along the Arkansas River. If you can avoid that stretch on the weekend, you'll be a happier camper.
Cheers,
Scott
