I just built a test run quilt out of 2nds lw ripstop from walmart and some regular 3/8 polyester batt and velcro from joanns. Less than $20.
I am 6'-3". I built it tapered top and bottom flat sides, 7' long with velcro at the foot/bottom, and a drawstring foot box. If you had a regular foot box you could make it shorter. Actually with a drawstring type I think I would like mine more like 1' longer than me.
I wanted to be able to open it all the way, thus the velcro and drawstring.
Its probably good for 60dF.
It works great, but the footbox being a drawstring type and tapered at the foot is slightly too tight. It would be better with a flared foot area where your feet end up.
If the bottom is open, IE tube, no problem. Of course if its open like a blanket it does not matter either.
If you want, I can post a pic or two.