So I decided to build my own artsy fixture.
I purchased an inexpensive 12volt LED dome light from a boat supply store. The LED circuit board inside was the right size to fit neatly in one of the picture frames I had already wood-burned and painted. I used a piece of MDF the size of the frame as a base. I drilled a hole for the wires, then painted the edges orange and the face with iridescent gold paint. The iridescent paint is to help reflect the light out from under the shade. (Why gold? Because I had it on hand.) I varnished the board, then attached the frame to it with screws from the back. The inset in the frame meant to hold the glass made a neat slot to fit in the shade. I attached the LED board with its original screws and glued down the switch.
To achieve a textured copper shade, I built a frame out of hardware cloth. I covered the frame with heavy-duty recycled aluminum foil, being careful to cover the inside with the shiny side out to reflect light. I pressed the aluminum into the hardware cloth for maximum texture. At this point it looked pretty disappointing, but I pressed on anyway. I brushed sizing all over the outside of the shade, then applied copper leaf. It took about 3 applications since the texture made leafing difficult. When I reached the point of good enough, I coated the shade with copper sealant, and left it to dry overnight.
Here it is, screwed securely to the trailer wall. Having little experience with electrical things, it was indescribably satisfying to flip the switch and see the light come on!