Larian Studios Forums Divinity: Original Sin 2 - The Modding Dungeon Divinity - Original Sin 2 - Modding General Bridge that you can walk under, how?

Just try different solutions. Maybe the two cliffs have ramps on each side to allow the player to go through a shallow part of the river?
The problem you have is actually an engine limitation.
But the editor is great and does a wonderful job at other things.
Cheer up!