For now, I'm trying to keep it simple. My buddy has a 24' enclosed trailer (Pace GT) with electric tongue jack, big battery on the front, both 12V and 110V lights inside, etc. He did not buy it new, and it had been "modified" several times along the way. It had a cheap battery charger installed in the trailer, with speaker wire running out to the battery (to keep it charged). Ridiculous.
The wiring on his trailer was completely screwed up the first time I towed it for him (to the point of blowing fuses in MY TRUCK) when I hooked up to it. He kept a box of 30A fuses in the top drawer of his toolbox to feed the trailer wiring a new fuse just about every time he used it.
In 2013, I spent a lot of time re-wiring and trying to correct all of the problems with his trailer. I got it to the point where it would no longer blow fuses on my truck when I hooked up to his trailer, but I still don't trust that trailer. The electric jack mostly works, but you still have to keep an eye on the "main fuse" on the 12V side of his trailer, or the battery will not charge. I don't think I'll ever be able to trust that trailer, but I do still tow it for him, and it's what I took to Bonneville in 2014, after doing a lot of re-wiring, putting all new tires & wheels on it, re-doing the brakes & bearings, etc.
Right now, I'm happy to use the manual jack on my open trailer, and to know that the wiring harness is completely intact. I need to add a toolbox to the front, modify the ramp pockets for longer ramps, and add some tie-down points. I'm also planning to buy/build one of those EMT conduit type canopies, and a handy way to carry it on the trailer.
This winter will be spent working on the new transmission, turbo, & injection pump setup. We are planning to run at Ohio and Bonneville in 2016!
Steve.