Been towing an 08 edge since new. I use a Brake Buddy and magnetic tow lights I mount on the roof at the back on the metal strip adjacent to the glass moon roof. I run the cable to the front, under the hood, and to the coach. They plug into coach harness.
Never needed a charge line. Battery is always up. For lack of a better way of explaining it, there are two accessory key positions. The one just before start activates all systems. There is a good battery draw at that position. But if you turn the key back towards the off position (with the tranny in neutral) one more position, it kills everything. Little to no parasitic draw down on battery.
Don't know if that is the same on newer Edge's. But has been bullet proof for me. Oh, and it has not registered any of the 20k+ miles I have towed her (on the odometer).
Sent from my iPad using iRV2 - RV Forum
2007 Newmar DutchStar 4304
Toad - 2008 Ford Edge