That this is going to be one harsh ride for that Airstream. 1 ton pickup might not be an issue for a 34' slide out given it's got some weight, but a 20 is like a flea riding on an elephant. I would consider a very entry level airsafe hitch or equiv. Now I would caution you, a lot of people...myself included, buy the cute small Airstream, then realize you know, I really shoulda gotten a 25 or 28. If you have ANY thought at some point on getting a larger Airstream (or other larger trailer) get a bit larger Airhitch than you need. Yes, it does push the connection back about a foot, but the ride is very smooth. You could use a Class 4 with what you have and have a bit of room to spare. I have the Class 6 and it's a monster and a PITA to get into the receiver, but my ride quality was unbelievably better and I stopped popping the occasional rivet after going to it.
I'll check with them in the morning, but just wondering, is the airsafe hitch adjustable for the air pressure? The class 4 is rated 9000 lbs.. 900 lb tongue weight.. Would it even deflect with the Bambi? My (33 ft.) Spartan is only 5500-6500 lbs on 2 axles.. I like the idea though.
For my two-axle, I've been looking at these; https://www.standardaxle.ca/product/...t013-143-03-2/
Now I see these ones; https://www.morryde.com/products/cre3000-triple/
What brave new world that has such things for old trailers..