This would depend on the type of vehicle but some questions would definitely be universal:

• What are their plans, where do they plan to tow/drive your RV?
• What is their experience in an RV, have they ever towed before?/Driven a large vehicle before?
• How many adults/children will be staying/traveling in the RV
• For trailers, what kind of tow vehicle and hitch do they have?
• Do they have campsites already organized or need suggestions?
• Do they have full hookups at the campgrounds/sites they plan to camp?
• Do they need any additional amenities or add-ons
• What is the distance they plan to travel?

help How to reservation RV Rental During a key exchange