IF you were flying at an AMA sanctioned field this would not be an issue. But if you can't go to the field, perhaps you can bring the field to you. And by that I mean to say, contact a local flying club and see if you can get a bit of help from a member to stand with you while you fly. A few times with an adult around might put an end to the problem. And perhaps the bullies might get to know the club members too. Just a thought.