No unfortunately they won't fit, and Ford (or any other aftermarket company) doesn't make any hitch covers for 3rd generation Explorers. Sorry for the bad news, but believe me plenty of people have inquired about this before. I really don't know why they don't make them.
I can tell you that it will not work, believe me I tried already.
I borrowed one
one day when I was at the Lincoln Mercury dealer, It looked like it could be modded to fit until I took one off and held it up to my bumper, the biggest problem is that the hitch sticks way farther on the Explorer and the cover wouldnt even begin to get close to the bumper, the other thing is the size of the opening.
I really think if someone would be able to come up with a aftermarket hitch cover they would sell pretty good