Hello Dan, glad somebody brought up the topic again.  I asked 
my dealer for any solution to the exposed propane controls
potentially corroding with time under the effect of humidity,
temperature, and of course road salt.  No useful answer.

Maybe we should ask Winnebago of VWoA.  I thought of 
periodically spraying locally with some protective
resin film. Were you maybe thinking of mudflaps attached
to the LP guard plate?  In winter time, when not using
the LP, how about wrapping the whole unit  with plastic? 

I have an additional problem:  the car body behind the
front wheels is getting damaged from road tar, back roads 
sandspray.  So thanks to Drew Farenwald, mudflaps are a
solution to this, I'll have to check into it.