Here is what I have come across so far.

1. Purchase the right adapter from the local trailer dealer for a good penny $16+.
2. Install a female receptacle on the trailer, build a male to male pig tail (unsafe).
3. Drill a hole in the trailer be it through the floor or wall, big enough to run a bare cord through and then make up the ends female to male one inside the other outside and conceal the other end under the trailer somehow.

Anyother ideas?

Thanks
Randy