Thought I would post this even though it may or may not be a new idea. Sort of a work in progress. I just recently bought a new cheapo tralior hitch cover for my truck that has a built in incandescent bulb for a taillight and brake light because all the led based ones only did brakes lights or were extremely overpriced locally.
Bully Brake/Trailer Hitch Light
Anyways I'm thinking about removing the bulb in it and replacing with an LED based setup. The bulb that it came with is supposedly a 1159 12.8V 1.6A bulb and apears to be a double filiment.
Now I'm not sure how to go about this but the original idea was to stick a small square circuit board with super bright leds all over it right under the red plastic cover. then wire it up directly to the covers wires. I also know I'll be needing some resisters to keep from overpowering the leds.
The second more easier option would to find a suitable LED bulb that fits into the same socket that the 1159 bulb used. I haven't found anything yet online :(
anyways more research is needed
Any input is welcome also.