Help Ways to reduce rope tunneling through meshes

[josemendez]

[...] or if the inner volumes of meshes could be "filled in" with composite convex hulls that can enforce depenetration better.

That's roughly what distance fields do: have you tried them?:
http://obi.virtualmethodstudio.com/manua...ields.html

They're designed specifically with the case of robust complex concave/convex collliders in mind. Unlike MeshColliders, distance fields are "solid", meaning they do have a volume and any particles inside them will be projected outside.

As a bonus they're also much faster than MeshColliders since distances to their surface are precalculated. At runtime, collision detection reduces to just reading from an array: no BVH traversal, no triangle/point shortest distance calculations. As drawbacks, they don't support non-uniform scaling and concave regions can sometimes produce jitter.

Other than distance fields, the list of things you've tried is pretty much complete.

Keep in mind that mass ratios still have a great effect of convergence: large mass ratios are the bane of iterative solvers like Obi, so they should be avoided at all costs. Large mass ratios will require more substeps to converge, making the simulation costlier. As a rule of thumb, no very heavy objects hanging from a light rope. If the mass ratio between them is larger than 1:10, either make the object lighter or the rope heavier.