Thanks for the answers and suggestions. I feel that letting them ride on the car as I ride on them ( uncovered) is the way to go. Currently they ride on the back of the rv behind the truck. I have a truck camper and have built a generator box which the bikes ride on with the front wheel removed. The pic shows the box on the back of the camper. Wife is just concerned about her bike getting dirty.
I agree a few minutes with a rag and there would be no dirt.