Hi Ash,
My understanding is, the rear tail light's can be left as red, with some of the owners reverting to an orange lense on the outer left and right side to act as a blinker (which may be purchased), leaving the back up light's as intended.
Again, these rules seem to have changed (or have been interpreted via varying engineers) that the back up light's (in the lower rear valance) must have a clear lense, however (again), a few owners have changed these to an orange lense which works as both a turning signal and back up light (dependent upon how its been wired up?).
If it gets down to the 'nitty/gritty', I believe that you may be able to purchase a LED light bulb which changes from amber to white (clear) depending upon the trigger pulse. That way you could run the clear lense with the LED changing to amber when you have your indicator on and changing to white when you select reverse.
Hope this helps...
Cheers,
Trans-Am:cool: