[Pyrotechnic]

I would look into using something similar that is readily available here.

Mentioned earlier in the thread were the amber RV tail lights. With some cutting and gluing of these and your original tail lights to create a hybrid, you could have something very close to what you want that is bolt in and requires no sheet metal mods. You will have to figure out the bulb situation and how isolate the red and yellow sections, but it sure beats body work.