OP again. It seems this topic has gotten a little out of control and I'm sorry that a couple of posters are perhaps less than happy with each other. All responses are more or less valid in their own way and I have taken them all into consideration. Again thanks for all your replies.
Now, here's what the seller and I agreed to do, and we are both comfortable with the agreement. I'll leave with his plate and registration and his written statement that I have his permission to be in possession of and use of his RV. My insurance policy (State Farm) says that I am covered when driving another persons vehicle whit their permission. When I get home I'll send him his plate, registration and that Star Bucks card. I'll leave him with a bottle of JD since I can't send that thru the mail.