Unfortunately there are no collision free prefabs we can replace on the bridges that wouldn't also take collision away for projectiles, players, and other vehicles. This isn't something I can fix from a map editor unfortunately. Luckily this is pretty rare, first time seeing this issue at all so the player experiencing drones might be living in a spot just elevated enough to hit the bridge on it's way from outpost.
I was able to remove the extra monument marker though! So we're good to go there. Thanks again!