I think he will be sorry. A few hundred lbs over weight, you can get away with, but 3K lbs, is more than a few lbs.
There is a solution - do not use the trailer. Tow the Explorer 4 down. Ford Fleet pdf says if you run the engine every 5 hours to cool the trans, the Explorer can be flat towed.
See page 11:
http://www.fleet.ford.com/resources/ford/general/pdf/towingguides/13FLRVTTgde_Oct19.pdfAnyone who thinks they want to tow a car on a trailer is fooling themselves once they get to the camp ground anyway. Dealing with a trailer is a pain. No reason not to flat tow the Explorer.