The stock lighting in the bathroom left a lot to be desired. I found this light on Amazon, it was setup with it's own base and wired for 120VAC. Not having room for the base I removed the base, drilled matching holes in the top of the cabinet. I needed longer threaded bushing that were from lowes. The light fixture is my 2nd one as I fried the first one. The 120VAC input stated 9-12VDC output. Thinking our rigs have nonimal 12VDC I wired it direct. It was nice and bright for the first few seconds, then the leds started to dim and go out. I measured the 12VDC in the rig and got 13.6 volts. That extra 1.6 volts was too much for this fixture. The 2nd one I installed a buck/boost transformer and set it to 10volts. All is well and happy now.
Light: https://www.amazon.com/gp/product/B00MJXXKS0/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1
Transformer: https://www.amazon.com/gp/product/B074J9D278/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1
