I definitely concur with the inclusion of the Grizzly. Put a good Cap 4 or above armor on it with full Vengeance or Purple Goddess guns/turrets and you pretty much have a light anti-fighter gunboat, especially since you can TS/TZ it.
As for the group, Penn is the kind of overlooked system in Liberty. Having people dedicated to patrolling it can only be a good thing.
I'd revise your ranking system a bit, though. It's confusing to see that Chief Deputy is below Undersheriff. Also, having a Deputy be a recruit rank is a little odd. I'd suggest the following.
As long as it's understood that a Sheriff is always above a Deputy, having Undersheriff outrank a Senior Deputy seems more kosher than an Undersheriff outranking a Chief Deputy. Additionally this boosts Deputy to legitimate group status instead of something that's looked to be passed on as soon as possible.