Can you title a salvage unit? I don't believe you can in New York (where we live)! Just asking!
There are many files that tell you how to do a PDI inspection - I'd follow those same steps.
Here is a start!INSPECT EVERYTHING; all appliances to make sure they are in working order, check for any leaks near the HW heater,check floors, walls, ceiling for any signs of water damage. Fill the fresh and black water tanks and check for leaks. Check tires to see how old/worn they are. Run the slide in/out a few times.
But most of all check to see if you can title/use a salvage unit on the road.!