Tink,
I would be fine with 2 F16's ... I can generally locate patterns that would work.
What I did this time around was take a yard of fabric, cut it into four 1/4 yd. pieces, then cut down the "fold" (lengthwise center) of the fabric. That gave me 8 F8's. They should measure about 9" x 22". (ladies, correct me if I'm wrong here, please?)
Well, that's how I did it, anyway. Hope this helps.
Odessa