Take your motorhome to a place that you can weight it loaded as you would for travel. Then subtract that weight figure from the GCWR of 24,000 the result is the amount that is actually available for a toad.
The figure available will probably be around 3500 to 4000 lbs I would imagine.
Why would you want to tow the Explorer Sport Trac on a trailer? The Sport Trac can be towed 4 down with the dealer installed Neutral Tow installed which is quite reasonable.
We tow a Ford Explorer 4 down and have for appox 28k miles.