I thought about attaching LED lights to my trailer and connect them up via the 7pin plug on my SUV. There is a reverse pin and the lights would come on while backing down the ramp. As for loading at might, I have a 12v 2million power spot light on the boat and I plug it into an accessory outlet. Lights while backing down the ramp and lights while loading.

Another option- Run a separate 2 prong plug to the boat trailer and mount the LED lights on the trailer. On the truck side female side of the two prong plug and wire it into a switch in the cab.