4) Remove its cruise engine (jumping and very slow normal engines only)
6) Prohibit barges docking at anything. This means that two people are needed to use a barge; a player driving a freighter or transport to load/unload the barge and the barge player.
7) Increasing its cargo capacity and reducing its armour.
Make that thing unusable for oe person, that way it definitly gets a team-only-effort...and with loading/unloading cycles it is still "there" so people can intercept it...