Well after a few weeks of beating around the bush I finally ordered some LED light strips. They are on the way from China and I'll be installing them next Friday. My method will be as follows, please point out any problems you might see or potential pitfalls...
I will be taking power directly from the battery with two leads of 18AWG wire, tucked into 3/8" black wire conduit and zip tie it every few feet to the propane line that runs underneath the entire length of the trailer. I will use an inline fuse (5amp) and a toggle switch will be installed, hopefully in the PVC junction box that the OP used in his install. If not I'll weatherproof it with hot glue and mount it on the outside of the box. I figure sense it is hardwired to the battery and will be hot all the time I should put a toggle switch on it in case the lights go haywire. The controller will be in the PVC junction box and be screwed onto the outside of the stair frame with the IR sensor pointing down. I ordered a 8ft extension for the pigtail that will run from stair frame up the door frame to the top of the door where they will connect to the light strip that will be held in place with the 3M double sided automotive tape and the sticky tape that the strip comes with. Hot glue the other unconnected end of the light strip for weatherproofing purposes and then see what happens All splices will be soldered, heat shrank and I will use liquid electrical tape where needed.