I'm sure you have something planned but here's what I do on the moto trailer
i have a latch and hasp on the inside of the trailer to keep the door shut. on the outside i just lock the

keeper to the

hanger if that make's any sense that way no one can lock you in using the factory installed pieces let's face it when ppl wanna lock you in there gonna find a way to lock you in regardless of what you do to prevent it. And it's bound to happen
As for electricity i ran all 12v light's and 12v heater's that are tied into two batterie's, they have a battery charger wired in in the same compartment. there are still two 120 outlets inside the trailer. then if you have the luxury of power hook-up's you can still have some "extra" amenities. but i can run jumper cable's from the truck to the camper to charge the batterie's if they need a little boost.
one of my race buddie's has a very similar setup but he went to the extent of building in a mini fridge and cut a hole in the front for a window air conditioner. as far as im concerned in northern michigan it's not really needed but to each his own.
I dont know if any of this help's at all but figure'd ide offer it