Only thread so far I can actually contribute too since I do not own a boat at the moment and still learning as much as I can so hear goes post number 1 :)

Not sure how new he wants to go but friends of mine have an excursion with a diesel that is a monster of a truck. I do not know the exact towing compacity but could be a way to stick with his want/need for an SUV over a truck and still have the big diesel engine for towing and piece of mind.

Yep excursion is the mack daddy.
The 6 leaker can be a PITA though and needs some large bugs worked out before they are any good.

i do appreciate everyones posts and im sure it will point out some things for him to consider before buying. Not turning this into a ford/chevy/dodge issue either but he will definitely be buying GM product so the Excursion is not an option for him - thanks tho.