Vented foot box in quilt cover?

I'm finally making some progress in the diy department.
I've nearly finished a quilt cover, which I slept in last night at home. I was happy at how much warmer it was inside it compared to outside it. I didn't need the quilt much at all, so it mainly just sat alongside my mat. At the moment I've been using a doona and a light insulated quilt on my bed, so this was significant.
(I went for the option of mat inside, so i still have the option of clipping the quilt to the mat if really cold.)
The last bit to do is sewing on the base. I have vague thoughts that it might be good to be able to open it up to let moist air out, keeping the foot of my bag drier. I'm wondering about a drawcord - probably the simplest. Vaguer thoughts re the option of a little hoop or stays or something for air circulation when not too cold. But that would add weight. Maybe a couple of tabs that allow mini tie-outs or something.
Has anybody thought about this??
Thanks for your thoughts.

(I went for the option of mat inside, so i still have the option of clipping the quilt to the mat if really cold.)
The last bit to do is sewing on the base. I have vague thoughts that it might be good to be able to open it up to let moist air out, keeping the foot of my bag drier. I'm wondering about a drawcord - probably the simplest. Vaguer thoughts re the option of a little hoop or stays or something for air circulation when not too cold. But that would add weight. Maybe a couple of tabs that allow mini tie-outs or something.
Has anybody thought about this??
Thanks for your thoughts.