Originally posted by Lithariel:

It is very hard to place building pieces underwater, especially since there is no diving mechanic, you can use console commands and force your character to fly underwater... but the camera gets stuck above water(which doesn't help).

Not really. You just have to use placeholders and get the camera angles to see the surface to snap to.

Originally posted by Lithariel:

One thing you could do... is build the bridge lower in the ravine. You could dig out some of the ground on both sides, so that the bridge sits overall lower in there.

Yeah, I already covered that in post #3, I wanted that height as a goal.

I created the topic to find out if anyone had tricks to finish without using iron or stone. I found my answer thanks to Mharr suggestion with the trees.