This is the kind of approach that I've advocated in a previous post.In my opinion, that is easy. I told my senior class that if they damage anything or do not clean up their mess, it is now vandalism and no longer a prank. No damage, no mess for others to clean, no problem.
If the prank was done with malicious intent that included any amount of damage then throw the book at them.
If not then have them clean everything up and at most it if there was any expense incurred because of the prank then the school should be compensated.