especially in a setup like that on a mainsheet. when you really need to let it go is in a gust, when the mainsail loads up and you need to blow it off. That's when I'm afraid the cam cleat is going to bite my hand off or the released line is going to burn thru my fingers.
I sailed a couple of seasons on Madeleine, a 65-foot tourist schooner in Newport, RI. She has a forestaysail on a boom, and on windier days, we sailed under that and the reefed foresail. The staysail sheeted to a horse just forward of the mast, with a cam cleat/block at the deck end. On windy days, I would lead the sheet forward and take a turn around the bitts, then step on it to pop it out of the cam cleat. That gave me full control and left my fingers intact. (OK, so I'm a wuss, but I still have all my fingers.)
I'm wondering if you could install a cleat or a hook on the cockpit well wall (one each side). You could then hook the sheet under it, step on the sheet to release it, and not have to get down on the cockpit sole -- and not have to put your hand right next to the cam cleat and block.