From issues that I found after I bought mine, check for soft spots in the floor, soft/discolored/rippled walls especially corners and around windows and other fixtures. Take a ladder so you can look at the roof. Check the underbelly for damage. Check systems - water, propane and electrical. Check plumbing for leaks. Below is a thread by JohnB on how to use a moisture meter to look for damage and leaks. It is highly recommended that you take a moisture meter with you. It is only about $40 but is well worth the expense. The more knowledgeable folks can give you more information. This is what I found from my own personal experience. I didn't know what to look for and ended up with a project.
Would this be the T1350 in Palmyra, PA?
The best of luck to you. Hope everything works out. The Sunlines are great campers. They are built well.