fitting at the rear might be possible, but i don't know how much space is behind there?
you'll need about 9" behind for the size of the bracket.
have a look in the original thread all dimensions are in there.
as for wireing off one remote yes it should be possible, you'll need to cut off the control box and extend the wires from the rear unit, to then splice them into the control box of the front one. then when you press the button, theortically it should send the signal front and rear.
key word here is therotically never done it or tried it so can't say either way. might be worth testing before fitting, then if it doesn't work you can sell the spare unit on and you won't have cut holes in your bumper for no reason