I have a set of Air Lift 5000# airbags on my 24'Class C to help with the tongue weight of my single axel cargo trailer. Your goal should be for the rig to sit dead level when fully loaded. You should always keep some pressure, 10 - 15# in your bags as they are not happy completely deflated and it will shorten their working life.
I air mine up to 50# and then drop the trailer onto the rear of the coach. When fully loaded with my Rzr inside along with a lot of extra gear the trailer weighs 2,600# and the tongue is exactly 16" off the ground and dead level. I was pleasantly surprised to find my unloaded {no trailer} ride and handling improved noticeably with just 15#.
The OP should err on the side of more not less tongue weight as sway can quickly become an issue especially with a toy hauler with significant weight that far back.
Works for me.
:C
