my Newmar

Sorry about all that rust on a new and very expensive coach. I'm sure I would concerned if that was my coach. I would make some phone calls to both Newmar and FCCC (chassis mfg?). Since most of the rust is on the chassis FCCC may be able to answer if it's safe to drive and what could be done to sand/paint what's there already to prevent any more.
Emails are nice for traceability and history of the conversations but I've found that I sometimes get a better response if I make a phone call.

Good luck