Thanks for the suggestions Lori. I clip the end mod biner to the amsteel line just above the whipping knot. I initially tried to tighten the corner cordlocks but found like you did that it produced too much tension and backed that off. I'm pretty certain the velcro slit was closed, but I suspect that the cold would have been felt in my upper calf area if that was the case, not the feet. So you don't experience the issue at all of the footbox extruding out and poking against the side of your underquilt? Maybe I'm just pushing my feet too far into the footbox. BTW, what temps have you gone down to with that setup?