There's a very good thread on this subject. I'd bring a pick and look very closely at the edges for soft floor/wood.
http://www.airforums.com/forums/f419...osy-39602.html.
I'm not sure the floor is plywood, I suspect OSB. Tires on that thing should be less than 5 years old, spendy to replace. Appliances all in working order. Is the body straight and without any major dents. The parts could be very expensive to replace because this was a very limited run of style.
I have been listening to the VAP episodes thevap.com, which have helped me a great deal. I am not certain, but I don't know if your Squarstream has a front hold down plate, I'd check for that as well since this is a longer Airstream. Colin Hyde is the specialist on the VAP and is a very good resource and could possibly have something in NY for you.
5K isn't much money for a ready to go Airstream in my humble opinion., but I'm not up on 80's and newer prices. My preference is 50-60s