Ragdoll exploding

I'm stuck with creating a ragdoll for an octopus and would love any help. The ragdoll works ok unless the tentacles start colliding with something or they're moved very quickly - then the bones get all jittery and eventually explode off into infinity in all different directions. I have about 6 colliders per tentacle. Things I've tried:

• Character joints

• Configurable joints

• Playing around with the masses and mass ratios of the rigidbodies

• Making it so that the parent of a given bone is the connected body in the joint, as well as trying the opposite for all bones

• Disabling preprocessing

• Enabling projection and tweaking values

• Changing default solver iteration (funny enough, the higher I set this the worse it becomes, which I think is opposite of what should happen)

• Creating a hidden reference octopus that has the actual rigidbodies and joints on it, and having a clone of the octopus use a trailing average of the position/rotations of all of the colliders on the reference to create a sort of 'smoothed motion' octopus

• Disabling collisions between the tentacles themselves

• Making it so that the colliders in the ragdoll don't overlap

I really can't find much online that helps with creating custom ragdolls. Any tips or things I should try out?