For your boat, just about any SUV with an appropriate tow rating will be fine. I towed my boat (1000 pounds more than yours) for years with a 4.0L V6 '98 Explorer, and never had a concern. Couldn't go over about 55 going up the 6% grades around here (well, I actually proved that I could maintain 65, but it involved some awfully high RPM's), but for anything else I had sufficient power and stability.
With the Expedition I have now, the boat has even less impact on performance/handling.
I'm going to agree with JerseyDave:
Pick a vehicle you like to drive solo first, then make sure it's up to the task pulling your boat.