The Class C will provide you with ample space and that includes those days when it is pouring rain or snowing and you are stuck inside. The Class C is also the cheapest RV you can buy and the easiest to load up and drive away.
It will add a couple thousand dollars or more to modify the Class C for towing a vehicle with the necessary brake controller and tow bar. An alternative is to mount a motor scooter or motorcycle off the rear of the motorhome or even a bicycle.
If you get a motorhome built on top of a Ford chassis with the E-350 or E-450 Class C motorhomes you can look online for problem years for Ford F-350 or F-450 pickups and learn about possible repair or maintenance issues before you buy something.
For your trip I would have all the belts and hoses replaced and have a front end shop check out the ball joints and tie rods and other key parts. I would verify that the tire jack worked and the spare tire was still usable.
You will find it easier to locate a MH in the SF area but you will pay more than for the same MH in an outlying area where there are fewer potential buyers.
