My father purchased an enclosed aluminum trailer yesterday and is looking at how he can get power inside the trailer on a long term basis. He was going to get one with power in it, but .
So, his current idea that I think sucks, is to drill a hole in the floor the size of the actual extension cord and then put an end on it so that he can pull some out that needed. It would be a 3 foot cord that he could push out of the floor or pull in. I see that as a road hazard as someday it would be flopping on the road.
I would think there would be an easier way or something much more sophisticated than that. All I have come up with is an exterior electrical box on the bottom of the trailer and one in the trailer, but then you would have to crawl under the trailer to hook it up.
He will not cut holes in anything but the floor.
All he is using this for is 2 battery tenders.
This picture is sort of what he bought.