Is this for a slide in camper and a trailer? If you can use a 7 pin in the bed of the truck, there is a kit you can buy to do just that. You disconnect the vehicle wiring from the 7 pin in the bumper and this special harness connects to the 7 pin and the original vehicle harness plugs into the new special harness, basically a T harness. It is several feet long and has a 7 pin on the end of it, which you mount in the bed.
https://www.etrailer.com/Wiring/Bargman/50-97-410.htmlhttps://www.etrailer.com/p-41157.html?hhyear=2018&hhmake=Ram&hhmodel=2500Older Ram trucks have the 4 way dangling from the harness underneath the bumper.
Charles
'03 Ram 2500 CTD, 5.9HO six speed, PacBrake Exh Brake, std cab, long bed, Leer top and 2008 Bigfoot 25B21RB.. previously (both gone) 2008 Thor/Dutchman Freedom Spirit 180 & 2007 Winnebago View 23H Motorhome.