I-80 route
My son and I flew the route roughly along I-80 last year on my first OSH trip (RV or otherwise) and would do same again, weather permitting, if I could go again this year. We got fogged in until after 10:00 am the morning we left the Bay area so ended up over the Nevada and Utah high country in the hot afternoon....a little on the rough side, so agree with flying early if at all possible, and O2 to fly higher would help too (we did it without O2 so flew that part at 11,500').
Rawlins, WY is another great place to overnight. Reasonable hotels within walking distance if another OSH bound pilot gets to the FBO's courtesy car first. We stayed there in both directions.