I think I'll just use one of these surface mount LED's and be on my way.
Sealed, 6-1/2" Oval LED Trailer Stop, Turn and Tail Light, Flange Mount, 10 Super Diode Optronics Trailer Lights STL78RB
Sealed, Streamline LED Trailer Stop, Turn and Tail Light, 3-Function, 11 Super Diodes Optronics...