The 5 by 7 meters rule was known to us last year, however we expected no problems with our big setup and only 4 camping tickets, and innitialy they left us allone.
Bugging everybody around us, except us, maybe they like the Dutch. But we cheered to soon as some suit turned up on I think it was Friday to bitch about our pitch and the number of cars without tickets we had on the plot. But i turned out to little to late and they gave up there complaints and left us alone, also because Robbo pitched right in front of us and he had plenty of tickets for all of our space.
If they really want to enforce this rule, they should put someone at the entrance gate of MB who really only lets people in with tickets attached firmly to the windshield and marked out pitches. Last year there was this kid standing at the gate checking tickets, he was easy to convince to let extra cars in, no problem whatsoever.
Just to be on the safe side next year we ordered 10 MB tickets, so we should have plenty of space for our setup.