yea patched all the walls and floors with help from a mod called Place Anywhere on PC. That mod makes settlement building the way it should have been by default imo.

It's too hard to do there because you can't get straight back up the cliff and have to walk around.

Most can usually walk back through the water.

If a couple get stuck because there is a rock at their feet you can either forget about them, try ringing a bell or put your weapon away and give them an encouraging punch with closed fist, which might get them moving.

Bummer.