In response to cochise49's original post ..
I have a F-53 and a 2013 CRV and in setting up to tow I learned ...
1.) The late model F-53's all come with one "standard" wiring harness that has a 12V positive spare wire from the Interior Dome Light switch on the dash that runs all the way to the rear in the wiring harness. It's blue and has a small ID tag on it and it is curled up in the harness and taped back. When you rotate the dome light switch up it will not only turn on the dome light if you have one ( I do not ) but also puts a 12V on the spare blue wire. Thats obviously what the installer used but neglected to explain. I chose to run a dedicated 10 gauge wire from my coach batteries to my CRV toad vehicles battery and fused it with a in-line 30 amp fuse.
2.) AWD with Navi have a constant electrical drain as long as the key is in the tow / Assc position. Pulling the fuse helps but does not stop it completeley. Only solution is running a hot wire from RV back to toad battery. Poor design considering they say to pull fuse when towing.