If you have the factory provided TPMS from Valor, call the Valor customer service department and ask them to send you a cable extension. I had the same problem and they sent me an expedited cable extension which allowed me to mount the antenna on the underside of my rear hitch. Works like a charm. As for the rust, I had the same thing on our Key Largo, and we purchased it in May. Since our coach was actually built in February I assume the frame sat outside in the Indiana snow and weather prior to the coach being built. The first thing I did when we got it home was to slide underneath and repaint all of the exposed frame with a good quality, black, paint.