Like everything, it depends.
My 24' Class C spent 9 days back in March parked at the airport on-property long-term lot in Orlando, which was no problem for $10/day IIRC. They even sign and advertise this lot being suitable for oversize vehicles.
The next time I did it this past June, in Pittsburgh, I got in OK, found a space to accommodate the rear overhang no problem as the lot was pretty much wide open, but when I came back 42 hours later, the place was jam packed. Still got out OK, right up to getting to the exit plaza, which had variable overhead clearance signed from 12' down to well under 11'. There was a ton of traffic there for it being midnight, so I was stuck in the lane I was originally lined up for, with an overhead clearance dimension of 11'-6". The lane was also at an angle, and the adjacent booth stuck out to the right curb line. Not good.
I lined up where I thought I needed to be, pulled both mirrors in, paid via credit card at the automated machine, and rolled through at 0.25mph, waiting for the inevitable scrape.
Which didn't happen. I must have had millimeters of clearance on both sides and the roof, as I nominally use 12' as my minimum clear height, based on a specification height of 11'-8".
I'll be sure to do a little more due diligence if I ever park at an airport again.
BTW, in Orlando I stayed at a KOA near the airport the night before parking as I had to de-winterize, and a close-by Wal-Mart either side of the Pittsburgh Airport parking experience.
