Re: Tow boat with Toyota V6
I towed with several Toyota 4x4 pickups for many years. In my experience, they did not stand up to heavier towing.
If your truck has a five speed manual transmission, tow in fourth gear. Fourth is direct through the transmission and using it helps prevent very expensive transmission rebuilds. Ask me how I know.

The transmission repair shop compared Toyota manual transmissions to sewing machines; in other words - light.
I also took out several rear wheel bearings on Toyota pickups, presumably because of towing. That truck did not have many miles on it either when the wheel bearings failed.
I had the same experience with Toyota trucks, all manual transmissions. They got noisy after being used to tow only a 1,200 lb aluminum bass boat. The dealer swapped out three, then the warranty ran out and I did 3 more, luckily the ex totaled it, it was getting expensive. A buddy owns a trans shop, he said it's about even between the Toyota transmissions and Ford Transmissions, both have a few inherent issues. Toyota has had a problem with weak planetary gears in the automatic, and Ford has sprag and OD clutch survival issues if not kept cool. According to him, the Ford can be made to handle a much larger load than the Toy can, if your talking automatics. From personal experience, all the Asian manual transmissions are too light, even those that Ford used which were sourced through Mazda and Asian Warner.
If your Explorer is sound otherwise, why not have a someone that knows transmissions upgrade yours a bit and you'll probably see another 200K out of that truck.
I've had 4.6L engines go over 350,000 miles.
From experience, the Toyota pickups I had were maxed out at around 1,500 lbs, and only good for short runs at that. With all the trans issues, motor issues, and ball joint issues I had, I wished it would have gotten totaled far sooner. That truck and the two before it cost me a bundle to keep going. After I moved to all Fords, I've had no further issues. The Fords are also far more comfortable than the Toyota, which never seemed to be built for a guy 6'3" tall.