I have not seen any you can purchase that install inside the wheel well. here is an idea, Get some 1. 5" square tube that can slide into the sides of the trailer hitch and mount rubber mudflaps onto the tube. When towing you just stick them into the hitch. Your going to have to figure out a way to hold the tubes into the hitch. YOu could drill and tap a hole in the hitch that you tighten a bolt down onto the mud flap tube (might weaken the hitch?) or maybe put a bolt into both tubes with the mud flaps attached to them, then run a bungy cord between the 2 bolts to hold tubes into hitch.
I do something like this for my slidin camper rear hold downs, only I drilled a 1/4" hole all the way through the hitch and inner tube that I put a pin through. My inner tubes extend out past the sides of the truck for the camper holddowns.