Problem with Normal Constraint and a Geometry Constraint while rigging (Orientation and World Up Type in sliding limbs)

[GiorgioNotaro01]

Hello, I'm writing because I'm encountering a problem with rigging a character that I can't seem to solve. Essentially, I need to make it so that the limbs can slide over the mesh to be repositioned wherever needed, similar to what's shown in Mindbender - the food  thief rigg video. The only idea I've come up with is to use a combination of a Normal Constraint and a Geometry Constraint to respectively orient and attach the leg to the mesh. Keep in mind that the base body will then be deformed by blend shapes and other deformers, so I believe this setup is the only viable option (feel free to share other ideas if you have any). The problem arises with the orientation of the Normal Constraint, which, once it reaches a certain point on the mesh, causes the leg to rotate 180 degrees. This happens because I can't figure out how to make the World Up Type of the Normal Constraint work. I've tried all sensible combinations, but none of them work. Even when creating a locator and setting the World Up Type as Object Rotation Up, the problem is that to make the locator stay in the right position, it needs to be parented to the controlling object that moves everything, and this causes a loop that leaves rotations within the group to which the normal constraint is applied. Do you have any solutions?

[mcw0]

Check out my file.  This might give you food for thought.  You'll notice I have a polySoftEdge and a polySmooth operation on the "egg".  The polySoftEdge didn't do anything.  But without the polySmooth node, the up vector calculations would wobble.  The smoother the egg surface obviously, the smoother the up vector interpolation.  I have some locators to facilitate some vector math to try to offset the wobble.  But it didn't work.  But again, hopefully inspiring more food for thought.  I hope my file leads you to a satisfactory solution.