i haven't made the bag yet, but i sat at work yesterday trying to figure out the same thing! (this is for the first shorter bag)
for the increases from 88 sts to 220sts, i think i'm going to do
round: [(kf/b 2 times), m1]* rep around.
(that is, knit 1 front+back two times, make 1).
doesn't that increase by 4 stitches for each 1 stitch, instead of 2.5? my theory was to *kfb,kfbf, rep from * across, reasoning that if i double the number of stitches by kfb in every stitch, that's 176, plus increasing an additional stitch on one-half of the total stitches (44) for a grand total of 220 all around.