Firing weapons while piloting boat?

I wanted to further explore the idea of a "water world" with a single island to battle over resources. One problem with this is the pvp aspect. Since there won't be many players, i was thinking of making a plugin of this sort to allow solo players to pvp.

I'm having issues understanding how I would go about this, since there doesn't seem to be a "Can hold weapon" bool that I can access/change. I have found one to see if a player is in a boat however.