I wonder if it would be possible to set an encounter, that players would have to OD roll to escape/avoid like a typical encounter.
Pick a square, Set up your group, that has a maximum of 3. (As a larger group would just get spotted/ignored, OR larger groups have lower OD threshold). Perhaps use a feature like distress for a check and to set it.
It would make it possible to siege Towns, with a large enough group. Yes, many will get through, some will not
You could also -mandate- it such that it's RT, giving players an opportunity to escape.