Joshua Tree to Baker City, Oregon

Were heading to Baker City after the 4th of July in our TC pulling a cargo trailer(5x8) I'd like to take the 93 N. out of Vegas but being the heat of summer I don't want to deal with the heat. I'm only wanting to do 3-4 hundred a day. So I guess my question is what way would be the coolest with camping spots along the way, boondock or CG's. Right now I'm looking at 395 the whole way. Still a lot warmth that way. Open to suggestions. Also any good campgrounds with hook ups along 395 so I can run my AC? I have a genny but prefer a RV park.
Also places that I can stop at along 395 above Reno on my route where I can get out of the heat would be helpful. I live in the desert so I want cool if possible in July.