>So, I'm assuming that 5500 lbs. is a legitimate weight when comparing engines.

Hfactor, don't forget to consider the GCWR, total weight of loaded truck and trailer.

That's a pretty heavy boat for an F150. How much does the trailer weigh? I might guess at least 1800#. Now you're up to 7300#. Add a 200# man, a 130# woman, two 60# kids and you're up to 7750#. You add in the weight of an ice chest, fishing tackle, water toys, camping gear, etc...and now you are way over the weight limit. Especially with surge brakes, that load will be pushing your truck all over the road.

Another thing to think about. Do you think that truck can pull that much weight out of the water and up a steep ramp?

FWIW, my coworker has the same truck as you describe and pulls a 24' fifth wheel that's 3830# unladen weight and rated at 5600# gross weight. He says the truck is underpowered and long steep hills are down in first gear at around 30 mph. That's slow enough to put you over with the semi's, but not enough power to pass them.

It's always better to get more truck than you think you need, because you're gonna need it. I would reccomend a minimum of an F250 with a 5.4 engine and 4.10 axle. The V-10 would be even better and is only a $600 option if you buy new.