I added a charging wire. Ran it from the front of the motorhome to the 7-pin trailer connector. Fused near the motorhome battery, and near the dinghy battery. I use a lighter-socket voltmeter in the dinghy so I can easily see if the power is flowing correctly.
2009 Fleetwood Icon 24A
Honda Fit dinghy with US Gear brake system
LinkPro battery monitor - EU2000i generator