If you rub a Ford GT back to bare carbon you will not get the beautiful weave pattern as exposed on the Ford GT Competition Special - the carbon is impregnated with a filler agent and the resulting bare body would look something like the green prototypes seen in the early days of development.
The panels for the Competition Special require extensive additional lay-up and time to create - not easy to reproduce after the fact, actually impossible to reproduce if you ask me! Only option would be to add a carbon wrap on top of the final body color.
AC - once again is not easy to install after the fact - I do believe the AC lines run through the chassis, but on the Competition Series, to save weight, they do not install the cables in the chassis - and as such they would be impossible to fit once a car was produced. Additionally there would be no 'spare' room to run the cables for an aftermarket AC set-up.
Hope this helps the AC vs Carbon Stripe debate - both impossible to replicate!!!