Do not buy it without having an experienced RV tech inspect it - period. Especially if you have little to no experience with RVs. You could pay one a few hundred $$ or so now, or spend thousands of $$ later fixing things you did not know about and wish you never bought it.
Water intrusion and rot & mold would be my #1 concern without question. It can cause very serious damage and in the worst cases, result in an unusable RV that would cost far more to repair than it's worth (think stripping down to bare studs). Replace tires and battery(ies) before moving it. A battery is a requirement when towing a trailer so the brakes will function (make sure all 4 brakes work). After that, perhaps water heater, furnace, fridge and AC unit?
If the TT was delivered to a site and never moved afterwards, that would suggest it was never taken to the dealer for any warranty work that might have been needed.
