I have lived 25 miles south of Tucson for 12 years so do know the area quite well. I also know many of the roads you might travel, and places to stay, as we have spent a lot of time doing that. Feel free to email or PM me if you would like.
OK, Giggle - aka Google - says Hwy 60 to the I10 all the way to Tucson. The one section I don't know is the 60 portion. And, very honestly, from Palm Desert area to Tucson you really don't have many choices. It is just desert.
If you want to come down past the Salton Sea - pretty much a waste of time in my opinion, you want to come down the west side and stay at Anza Borrego SP in Borrego Springs. Great place; probably need reservations. Yuma has several places - we like The Palms. Then not much until you get to Gila Bend and Quail Trail is good. On on to Eloy area and Picacho Peak staying at the rv park there or one that has turned into a KOA in that area. Then into Tucson.
If you come across on the I10 go south on Hwy 85 just west of Phoenix to connect up with the I8; avoid Phoenix and their traffic and all. Leaf Verde in Buckeye near the I10 / Hwy 85 intersection is good place.
In Tucson you might try getting into Catalina S P; we go there although it is only just north of Tucson and 45 miles from the house. Neat place. Otherwise I would recommend on that used to be rv dealer owned and now a KOA in the center of town or Rincon West.
If you are going east from there I can offer help if and when you want it.
In Tucson there is a lot to do but do not miss the Desert Museum. Again, if you want help just email or PM me.
We are heading over to Indio, CA for a month soon staying at Indian Waters - will catch Leaf Verde going over and coming back once again. And, once again, when we get back we will spend 5 nights at Catalina.
Enjoy!