theres probably not much you can do for this, even a lawyer cant really help get you completely out. lawyers are only good for getting you less fucked in the ass.

trespassing IS illegal, and if they talk about it in court they may tell you somethin about columbine, i was in court once and they busted a kid for trespassing (although he was there to register for classes) and the judge talked about columbine

and searching your car, you have the right to say no, but yes they will get a warrant or police dogs, who then sniff ur car freak out and then they have probable cause

fuck the police.

also, if your weed or pipe are sitting out on the seats and are visible, thats probable cause to search your car.