Consider getting a professional to inspect the RV you have a great interest in buying. Yes, they cost but you'll have some peace of mind. However, IMO "looking good" usually means the RV has been taken care of by the owner such as roof maintenance, oil changes etc.
Trailers are usually less expensive than Cs and As. An appropriate size trailer depends your SUV numbers....look at the driver's door jam. Two most important numbers are max payload and max tow weight.
Move along quickly, kids will be back in school very soon!