I would NEVER buy any RV or other vehicle without a thorough test drive. I need to now how the engine runs, hot and cold, how well the transmission shifts, if there is vibration at low or high speeds, how well the brakes work, etc. etc. etc. etc. I would interpret any reluctance on the part of the owner to let me drive the rig as ipso facto proof that there was something wrong about it that he didn't want me to know.
You see, in this kind of private transaction, there's something called "asymmetry of information." The seller knows more--MUCH more--about the vehicle than the buyer does. The seller, to address this, should offer some kind of assurance. Many used vehicle dealers offer a warranty. If you are unwilling to do that, then being willing to offer a test drive connotes honesty and sincerity. Conversely, being unwilling or reluctant to have a prospective buyer drive the vehicle connotes dishonestly and suggests that you are concealing something.
So how do you "deal with" this? Simply quell your existential fears about someone else driving your rig for a few blocks and realize that no sane buyer would ever even think about purchasing an RV unless he could take it for a thorough test drive. Remember, it's not all about you and your fears. The buyer is at least as much afraid that he'll be buying a rig that, it will become apparent, needs $8000 worth of work.
