I really don't think you can move the hitch w/o looseing use of it. If you were able to put it on top of the lower frame and use spacers it'd be weaker I think, and the only other way I could think of would be to buy a hidden hitch and use it, they bring em up to like a normal hitch height/below the bumper on body lifted vehicles.
Another idea on the bumper maybe to lift it's brackets and only use 1 bolt in each bracket, meaning take the lower bolt hole, move it to the top hole in the frame and bolt it down. I'm sure it would require some cutting. Either that or cut and weld em up.