view obstruction

[Solace]

I was wondering - I've seen a couple teams that use large fabric sails to bush boxes around on the playing field. My question is (if these sheets are opaque) what will happen if a team using such sheets were to unfold them and position themselves directly in front of the oposing alliance's driver station, effectively destroying all visibility of the playing field? Would this be against the rules? (cause it would definitely make people not like you...)

I'm not pointing any fingers here - teams that have used sails most likely did not have this in mind when designing they're robots. I am only asking this question because i am concerned about a possible strategy that is (i think) currently allowed and would completely destroy the spirit of the competition.