Philip -
Wow! What a job! You really wrapped it up and tied it with a bow!
I did the same thing in 2006 - see Post #22 in this thread.
http://www.trailmanorowners.com/foru...ead.php?t=4909
Rather than using really really heavy wire, like #2 or #4, I went to Lowes and bought a 50-foot 10-gauge extension cord (it was cheaper than 10-gauge wire), cut off the plug and socket, and threw them away. I then wired up both ends of this cord as you described, cut it at the tow vehicle bumper, and put in an ordinary boat-trailer plug and socket. As has been noted, you need a circuit breaker or fuse on both ends, so I did that, and I also put an isolator relay in the tow vehicle. The whole thing worked like a champ!
I'm sure I didn't get as much charge current as you get, but I decided that if the TM battery maintains a few amps of positive charge current with the refrig and fan running, all would be fine. And it was - I never had another problem.
I made the job harder than it had to be by running the wire inside the tow vehicle, under the carpets and in existing wire channels. I wouldn't do that again. But other than that, the job was a complete success, not too expensive, and not too difficult.
Bill