We had the same issue at a different air show. So, I called, spoke with the appropriate person, described our "B" as a "conversion van". In the end we agreed that I'd send them photo, they'd provide the photo to the "gate folks", and it all worked like a charm.
It was a military base, so that may have been a help with "the system".
The policy was also "no RVs", but they treated us like a "van".
We didn't roll out the awning, start the genset, or anything else that would draw attention. But, it sure was nice to have - on site - our own "refuge".
Cheers.