It's possible to hold the bridge between the carts, yes, however you should consider then your making it so that it's the sole place to Cade and are reducing the space the player has to fight before being routed to the defensive line. Adding additional spots on the player side of the river allows for them to fight on the bridge and retreat extending the Fight from just one location to a larger portion of the map.
In short, I would say you should add some barricade locations near spawn, for example in screenshot 1 you have an open bank along the river you could put a small defensive tower in [look at the tower near the nord spawn in ancient bastion as an example] or etc. other things on your map.
In short, I would say you should add some barricade locations near spawn, for example in screenshot 1 you have an open bank along the river you could put a small defensive tower in [look at the tower near the nord spawn in ancient bastion as an example] or etc. other things on your map.