Could add some arty to both sides? 1 piece each.
Right now vehicle balance isn't that bad imo. If a Panther is locking down the bridge, then that's partly an example of a player doing a good job of using their assets to win the game.
But I can see it being tough because of the Panther's frontal armor and having a great field of fire from there, so maybe arty could help counter that and get it off the bridge to be flanked and killed.