In my opinion, LEDs are the only option. Now, if that doesn't fit your budget, there is nothing you can do about it, but if you can, and just aren't sure if you want to spend that money, I am telling you that you want to.
If you don't go with LEDs, always unplug your lights before putting the trailer in the water, even if they are submersible (submersible lights are sealed better keeping the water that will get in anyway from getting out as quickly). Personally, I would drill some drain holes in a set of submersible lights.