Essentially what Chris did is the way it's done (mine are even higher and sometimes aren't far from getting wet). Only thing is just get the el cheapo lights from Walmart and use PVC cement for any joints. I have no joints just PVC pipe bolted to the trailer guides, goes straight up. Dab some grease on the bulbs where they plug in (Dielectric or "tuneup grease" preferrably). Bring the ground wire all the way to front of the trailer and connect it to the trailer to truck connection. Keep the lights dry and they will not fail that way. They will be trouble free for many years.