Explorer + 7000 lbs. towed = failure. The first thing to fail will be your nerves from the poor braking, handling, and towing performance. The next will be drivetrain and suspension of the Explorer. The other failure that may happen is catastrophic accident because of the weights involved.
It is terribly difficult to estimate proper towing performance from anecdotal experience posted on this Forum. There are users that believe a good towing setup is Mom's grocery-getter, as long as it moves in Drive. There are others that believe anything less than a diesel 1 ton is inadequate. If you're looking for a new tow vehicle, I would suggest to get out and drive a couple, hooked to your TT. With the exception of a few, there aren't any SUV's that are going to be well mated to 7K lbs.