CB radios may be “old school”, but having one in the coach proved to be worth it’s weight in gold when (pre TPMS), a trucker called us on the radio to alert us to a flat trailer tire. Also, finding out about an accident in real time vs. Waze, etc., is a nice feature.
As for the ground plane, I have not been able to find info on what, if anything, the antenna is connected to other than the roof. Our coach is an 08 Camelot 42pdq.