FlintStryker

I assume you've seen this already, but in case you haven't: http://www.nexusmods.com/skyrim/mods/35094/?

Sorry to necro an old thread, but I'm curious: would this even work? Because I can see some advantages to doing this if it would work, but I've never seen an edge "fork" into multiple triangles, one above another. I'll have to try this out when I get home. IF this can be done, I think it would solve a lot of problems that I've had with deleted triangles causing edge triangles to get renumbered, thus forcing all adjacent navmeshes to change their portal data, thus creating dirty navmeshes that break mod compatibility unnecessarily.

Check out SkyRealism Crafting Kits: http://www.nexusmods.com/skyrim/mods/21866/?

megageeklizzy has one that will give you a good head start: http://www.nexusmods.com/skyrim/mods/67661/? I'm not sure if she's still working on it, but she's already said that anyone has permission to pick it up and modify it.