Hey Patrick,
I'd figure the boat, fuel, gear and anluminum two-axle trailer should weigh around 4700-4900lbs. You should have no problem with either of your vehicles. You may be close to the max, but for short distance should be no problem.
Just for your information and comparrison, I purchased a 2000 Hammer, new in 2000, with a 350Mag for 25,400 plus trailer, tax, etc.....
With the 7.4L and trailer your price isn't too far off. However, for a 2000 model(now being 2002) I would think you could go just a bit less with a little work.