KATOOM

I'm curious as to why you didnt got with the common airbag set up. Or.....Timbrens.
The pin weight on my trailer is around 3k and I have Timbrens. That said, the ones which came in the kit for my truck wernt stout enough but Timbren took care of that for nothing. They'll custom fit for you if you need something specific. Works perfect and I hardly know they're there when the trailers parked.

I say this because years ago I fit a heavy camper on a half ton 4wd. Nothing as heavy as yours but still to big for the truck and the suspension wasnt happy. After trying to find a reasonable way to increase suspension capacity, I ignored someone offing advice about Timbrens and fully swapped out stiffer springs. Eventually I got it to work but the unloaded ride was very stiff.

Not saying you did it wrong but just sharing a story.