Expedition Tow Vehicle - Doing the Math - Will it work?

Sure seems like your too close to maxed out to me personally.

A 32' long rig is a lot for a standard wheelbase expy, I had one and it towed my 6k, 23' Layton great, but it felt maxed out and I would not want much more weight behind it than that. Also 530 lb tongue weight seems awfully light for that rig. Most tongue weights are 12-15% of loaded trailer weight. Good luck with your decision