18 wheelers and wind make the trailer move the LX. It doesn’t go into a sway pattern, but moves the truck around in sketchy ways. No wind no problem, but we visit very windy SW Wyoming often. I imagine a long wheel base 2500 duramax would solve all problems.
I don't have an Airstream but I have a 25' Lance trailer. The weight, frame height, and overall dimensions are similar to a ~25' AS.
If you're getting sway I'd recommend a different WD hitch. Or start with double-checking your setup and the tongue weight you're running with whatever setup you do have.
I had a ProSeries hitch on my old trailer when I first got the LC, which had a friction anti-sway device. It was OK but when you passed a semi it would definitely move you. If you were on a 2 lane road and the semi came the other way it'd shake you as it whipped past. We did 2 years with that - the first year with the stock suspension and the second year with a 2" lift.
My current setup on the newer trailer is a BlueOx hitch. I get no sway from it. Literally I'll drive between two semis on the highway at 75MPH with one hand and feel no sway at all. On 2 lane roads at 60mph I can pass an incoming semi and... NOTHING. I've put close to 15k miles driving from Illinois out west the CO, UT, CA, AZ, etc over the last 3 summers and the LC handles it marvelously. I wish I'd bought the BlueOx hitch out the gate.
A good hitch properly setup will let you run a 25' trailer on an LC or LX just fine. You don't need a 1 ton dual cab pickup with an 8' bed. I can set my cruise at 75 and nearly forget the trailer is behind me (except when merging.. no way to hide that weight). I'd drive faster but the trailer tires are only rated at 81MPH and so I try to give a margin of safety.
Note: The only time I do get any sway is if some jackass in a van comes up on me going 20-30mph over my speed and gets kinda close I'll feel the ass-end of the trailer wiggle me, That's pretty rare on cross-country trips but here in Illinois I might be doing 70 with the trailer in a 60 zone in one of the right lanes and people will pass doing 90-100. No kidding here... Illinois doesn't apply points to your license unless you've had 3 violations in 12 months so you can get caught driving 120MPH twice a year and all you pay is the ticket. (FWIW I think the wiggle is in part because I run on the high end of recommended tongue weight so there's less "stabilizing" the rear... when I'm carrying a full grey or blank tank which is behind the rear axle I don't recall ever experiencing this).
