Like the notion of the docking connector (male on the outside of the trailer).
I've not got past the painting part of my trailer, but I'm still collecting 'stuff' to go in it.
Latest goodie is a "Rig Runner" from West Mountain Radio. Designed for powering ham radio stuff on 12VDC. Pretty spiffy item.
See
http://www.westmountainradio.com/RIGrunner.htm