Just an idea.
I personally think it would be a good idea, if everyone at 4.20 stopped smoking weed for awhile, and sat around and debated or talked about what they could do to promote awareness. Then hopefully as a result of this, more people can join the group and come along and support it. Like my self for example, i think people should be able to smoke, however i choose not to so i don't really want to come along and have smoke blown all around me, im sure im not the only one. perhaps then police will have no reason to harrass you guys and be dicks, if you are not smoking and do not have weed on you. (you can still come to the group wasted). it also won't look as bad to the conservative students or for the uni as you will just be harmless protesters. however then hopefully your numbers will grow, and they won't be able to ignore you for much longer.
p.s: its not a good look to have people smoking in the corner of the union lawn it looks dodgy :). and just confirms peoples ideas about what they could be already thinking.