Strengthening rear suspension for towing

[Mooseman93]

I think a set of AirLift1000 air bags inside the rear springs would do the trick. That's what I did on my 01 Yukon XL and it made a world of difference for towing.
For background, I cheaped out when my stock autoride air suspension crapped out like they do. I put on those same coil assist shocks in your picture to try to compensate for the lost spring rate the old air shocks provided. They didn't help much if at all. Very saggy when towing my boat. 2019 I got the air bags and have been very happy with the results.

And yeah, that short wheelbase you've got probably would be a nightmare for sway control but that's not the question you asked so no lectures from me.

 

[miami592]

Moog 81069 rear coil springs, these are the equivalent of GM HD springs used on Z71s and later generation ZW7 without Nivomats. 45H2164 for ACDelco Professional.

Isn't that Moog number the right one Ron? @OR VietVet

I put these same springs (with Bilstein shocks) on the rear of my 01 Yukon 5.3 when my Nivomat shocks crapped out. The rear end does sit an inch or two higher with that setup when I'm not towing. When towing my 4500lb camper, it sits nice and level. I also use a weight distributing hitch.

Personally I would not tow that car trailer without a WDH. About 20 years ago I saw someone lose a classic suburban they were towing when the trailer swayed & flipped out of nowhere.

Hope this helps,
Jeff