There are several Ford connectors along the drivers side, under the dash and hood, that are part of Ford's RV Conversion Package. These connectors are for items like rear A/C, lights, constant 12volt power, ignition "on" 12volt power, brake controller, etc... Your van actually came with a wiring diagram/schematic and the various connectors with pigtail wiring to connect to these Ford connectors. While SMB uses some of these existing connectors, most are not used because the majority of the SMB components are powered from the house battery(s), not the starting battery(s).
I hope this helps.