Hey Curt, when you complete this modification and are happy with it, please post or send me a shot of the setup. I have a couple of these beasts as well, this would be a nice way to make them much more useable. I especially like the idea of the overload spring - are you thinking of a flat bit of steel? I've seen posts that recommend drain cleaners as a source, or perhaps a thin saw blade. With enough curve in the steel it would take up the space when the thinner holder is in place.
Nathan