Thanks for all the replys, I dont want to leave the space, I can't expect the owner to back me up and I cant talk other bands into respecting my amp because they don't seem to "see" the point...and I have better things to do than hide all day on the rehearsal space... though I'm starting to contemplate a "warning" that includes their equipment and human feces 
Any way, things being they way they are, what I need is to find a solution that will speak directly to their lizard (drunk-ass) brain and makes them NOT put anything over my amp... Cover+ inestable top (cable mess, foam or something weirdly shaped) is the best idea so far... I keep fantasizing about a top of nais with the words "share my hepatitis C" sprayed over it...

Any way, things being they way they are, what I need is to find a solution that will speak directly to their lizard (drunk-ass) brain and makes them NOT put anything over my amp... Cover+ inestable top (cable mess, foam or something weirdly shaped) is the best idea so far... I keep fantasizing about a top of nais with the words "share my hepatitis C" sprayed over it...