Best to be on paved parking
When you look up under the MH you will see that Airstream used steel tubing for the under supports of the floor base plywood. They will be rusted, but should be OK and would be best if the unit was parked on some type of solid parking media. On the grass, will for sure be rusted good. The 82 used 5/8" plywood. Look in the back windows and try to see if the plywood flooring under them is not rotted out. On the outside of the Motorhome, you should find many rusted steel screws, that you can replace in time with Stainless. Other than that, just look for leaks around windows and roof vents and such.
Good luck with the unit, and hope all work out OK!
If you want to PM me with your phone number, would be glad to talk with you about the 310!
Chris & Brenda, Members of the Christian Motorcyclists Association
AIR Member 12654
1982 310 MoHo
Many Years ago, 1972 Argosy 24' trailer
Our Toad, 96 Saturn SW2 (250,000 and still going