When I initially went back and forth between Carli and Thuren I landed on Thuren for a few reasons but one of which was because I didn't want a full 3.25" kit so I could get the 2.75" with Thuren.
Sag is my primary concern. I do get a bit of body roll around the corners but I think that is on me as I had them soften the shocks up a bit (there were a few other issues with the Kings I ordered but I had them softened a bit while they were out there).
I put 400lbs in the bed and she sags quite a bit. I've got a 7200lb 32' camper I pull, and even with the WDH cranked, the thing sags a lot. I had a fiberglass topper with a rhino rack and a roofnest falcon, ton of sag without anything in the bed. To be fair, Chris at Thuren asked me what I was gonna do with it and I decided on the softer springs, but I'm surprised just how soft they are. I think my 1500 leafs were way stiffer than this thing.
As of this moment I'm still debating on a cap or not. RTT isn't the life for me I don't think, at least not the version I had. I'd be more interested if there was a version where I could leave my bedding/pillow in it, because otherwise it's basically a tent at 10x the price.
If I go with a cap and whatever in the bed I'll likely go back to the stock rear coils, Thuren's do mid-rate stock height coils, look at the Carli 2"+ you got, or just add airbags, depends on how it sits. I'd like to only leverage airbags when there is additional weight, I don't want to be sagging without anything in the bed and having to use the bags all the time, so I need to figure out what I'm gonna do on this build before I keep tossing money at it.
The rear coils right now are perfect, so long as it doesn't have a load in it. So if I do just a tonneau then I'll keep these and add bags for towing the trailer. If I do a cap I'll likely have to mix up my rear coils a bit.