In actual fact some of the spotters are ATCO's! Quite a few don't actually see the aircraft they control and take an interest in seeing the real things at airports.
I can't condone parking in front of emergency exits etc. but if the paranoia about security subsided a bit I think spotters would be only to happy to park legally in a designated spot on the perimeter. Some people give the impression that they'd rather tolerate muggers and murderers rather than spotters, whereas spotting is a totally innocuous activity.
All it needs is a bit of tolerance and goodwill.