Why not mount them off a front hitch.
Because I don't have one and don't want to spend the $ to have it put on. Also I'd rather not have the bikes line-of-sight in front of the truck.
I guess my options are:
-bikes ride in the TT with blankets over them
-bikes ride on the back of the tt bumper w/ a welded or bolted on rack
-bikes ride behind the truck on the hitch (seems to be least desirable).