I was just messing about trying to do the route with all the quests and uh, turns out you can just kind of jump over the water under the bridge.

The little patch of land is entirely possible to get on to, and jumping over to the other side is relatively easy enough. It makes you go out of bounds and when it brings you back, you get spawned at the checkpoint on the other side of the bridge.

After that you just, quickly move the witch, get the Motherboard, get the Humanboard, do the parkour and you're practically done with the run :3