Some years back there was a fatal Pawnee glider kiting accident. I had the opportunity to inspect the skeleton of the Pawnee, it had been consumed by fire, at the aviation wrecking yard. I wasn't permitted to take photos.

The Pawnee had two Schweizer hooks installed on a plate and connected to the ship with a flat metal strap that could not have been more than 1/4" thick. During the kiting, this strap with bracket and hooks, bent upward. This put enough slack in the release cable so it could not activate the release. It bent the hook up so far it impacted the rudder and bent the rudder frame upwards several inches.

I mention this as even if you are currently using a Schweizer hook, whichever way up you have it, it still needs to be on a mount that's designed for towing gliders, not just banners.