Why dont u just try getting away when the police comes, seems to be the easiest way to ride and try to get away, for me in Sweden this just sounds so bizzare.
The things iv'e been told for riding trials is
when i was backwheeling on a concrete ledge with flowers and stuff ontop
"hey, cool stuff your doing show us one more time"
when i was backwheeling a rail a friday night downtown
"it's better your out riding your bike and training tricks instead of being drunk and fighting"
"show us some cool tricks"
once one of me friend got asked to do something cool by the cops so he did a 180 and hit a bikestand and about 20 bikes fell over and the cops just laughed and didn't give a piss about it. (N)