svalgoma

I have a wheelchair lift installed on my car, not the motorhome, but it is wired directly to the battery with 8 gauge wire and a 30 amp thermal fuse. Your 7 pin isn't even close.

The owners manual for the 2015 Ford Edge specifically says you have to disconnect the negative cable to the battery if you are flat towing. I guess they heard the stories of flat batteries from other owners and this is their fix. Doesn't help if you have an auxiliary brake unit that needs power so I guess the best option is to add a charger as Walt mentioned above.