I'm back at it with the overalls and decided to try a different nip-slip-prevention method for these. Instead of "gluing" the fabric to specific parts of the skin, I'm adding an invisible strip of fabric between the two straps. The downside is that it's always there and can't be turned on or off, which I think is fine in this case. Another downside is that it's not as foolproof as the "gluing" because the fabric can still slide about relative to the skin, but that also prevents unsightly crumpling.

-- I'm not mad at you, just Westphalian.