As with any RV there are several issues that rise above the rest, and if you do a quick internet search you will find them, but here are a couple.
1. Water intrusion is a death sentence for an RV. If you see any sign of water damage inside or out...pass 'er by. (Look for delamination on the fiberglass exterior, stains on the roof of the interior. Look around water fixtures and toilet.)
2. Seals! Windows, doors, vents, clam shell halves. (Think water intrusion)
3. Observe the seller opening and closing the unit.
4. Excessive wear anywhere
5. Signs of exterior damage (especially at the corners).
As for the tow vehicle:
There are several factors to be aware of, this is a good article on the subject.
https://camperguide.org/camper-weight/
When I used to sell trailers for a living, I would ALWAYS recommend at tow rating at least 15% above what the trailers GVWR was. (if the GVWR of the trailer was 5500 you should have a tow capacity of AT LEAST 6325 LBS.
my $.02