My dealer was mod friendly, until my headgasket blew.

 

"isnt the coupler adjustable on the goose neck?"

It is but its a new neckover 40ft and it doesnt go up as high as most of them do, id have to find and buy one or either make a special one with a latch system that doesnt stick up as high on the side of it so you can slide it up further cuz the pin sticks up on the side pretty high so it can only slide up so far

 

You may want to start a thread in the suspension area. It might get you some more answers.

https://www.dieselbombers.com/tire-wheel-suspension/