Sure; a good fabricator could probably cut off the brackets, move them back, and re-weld. But that's not going to help you, because the true footwell IS under the front seats, then you have a shelf, and then the back deck. If you moved it back and the passenger had to put feet on the rear deck and that would be like sitting on the floor.
Why would you want to? You have to ride in the back seat of your own Jeep?