I just upgraded my Furrion S rearview camera with the S+ and a 7-inch display. Huge improvement in resolution, features and display brightness over the original S and 5-inch display that was OEM (and basically worthless)!! The S+ camera slips into the old S housing so no mounting of the new housing on the exterior of the trailer and no rewiring needed. Since my TV is GM with the trailer camera functionality, I seriously considered going the way of this original thread instead, but my GM screen is small, and I can mount the 7-inch Furrion screen partially over the rearview mirror which isn't useful when towing and retain my TV display for the TV cameras. And again, no rewiring was necessary.
(I thought I saw a prior thread where someone else did this upgrade but could not find it.)