Your goals are well doable. The electrics of making the car run the RV are a bit beyond my ken, but charging the car from the generator is easy. As for buying one already converted, you may have trouble finding one in your area. EVs are not super common yet, so looking for one is a roll of the dice to start. Then you narrow down to a VW Bus, and that predictably makes your pool much smaller. I believe there's a sale section on http://evalbum.com that you might try to take a look at.