I travel I-95 extensively between Philly and Jacksonville. The place you saw is DonMar. I have stopped a few times in the past. Felt his pricing on the used units was too high for the amount of work they required. They used to be an Airstream Dealer quite a few years back. The old man that owned it has died, not sure who is running it now. A lot of those Airstreams came up from FL when they closed down one of the AS only parks down there about 6-7 years ago. Ditto the Spartans.
Not sure where the bone yard one is, I have never noticed one. There is an RV salvage yard outside of Greensboro, NC on US 421 that has a lot of Airstreams but he won't part them out, just wants to sell whole units.