Prestwick? I think MOL (of Ryanair fame) might have something to say about his (few) scheduled services being potentially interrupted by fast-jet jockeys showing off.
Parking (cars rather than aeroplanes) might be an issue as most of the larger spaces are already used by airport-associated long-stay outfits - only the patch of ground beside the tower security gate comes to mind, and it isn't 'large' as car parks go.
I know the railway station is close, but if public access were to be from the Gannet side as opposed to the terminal side, it'd be a bit of a hike for some... 2+ miles.
As for RNAS Prestwick/HMS Gannet SAR, mentioned earlier, (thread drift...), are it's days also not numbered, with civvy contractors taking on that role in the not too distant, and potentially from elsewhere?
Any other non-mil airfields having commercial/scheduled operators holding similar shows?