Boy, talk about scale/thread drift!
Can’t say as I can add much to what has already been said; however, I think you’ll be happier in the long run to use the largest curve radius that you can fit in the space allowed. It would even be worth a set of good diamond errings to get her to allow more space!
I noticed your reference to natural materials for buildings. If you haven’t gone yet, go immediately to Chicago Botanical Garden and check out the railway there. Every structure, bridge, building, etc. is made using twigs, shells, nuts and such. It’s truly fantastic what they accomplished. Take your camera!
Paul Nevell