Include a large rental deposit if renters want to serve food. The damage deposit becomes non-refundable if extracleanup is required (Make sure it covers the cleanup cost, carpet cleaning, seat cleaning/wipedown, rental revenue loss due to clean-up time, and a little extra to make you feel better. ;)
The article that gaftaper posted has some frightening implications. Based on my experience, the bell curve the author talks about is true. The emphasis to find and teach (create?) effective emergency leaders becomes therefore a critical component, in my opinion.
How about using drywall joint tape instead of masking or gaffer's tape? Will it be removable after 3/4 weeks on stage? And what brand and width masking tape that will not wrinkle/pucker/shrink is being used?