sounds involved,,how about just makeing sure the toggle rope is big enough to not wear through over time, 1/4" is sufficient, and that the hole in the hull is rounded over well without a rough edge. Production kayaks with 1/8" lines are crazy. My Mariner has a 5/16" braided nylon line through a u-bolt to the toggle, it's lasted 10yrs. I've seen 5mm polypropelene lines on british boats worn through in a year because the hole was too small and rough. A 1/4" line through a 3/8" hole can last a very long time with plenty of notice that it's wearing through.

A toggle line can't be getting that much use unless it's a tie-down anchor on a roof rack. Anyone carrying a kayak with another person for a distance is probably using their hands or a good solid line in a toggle.