Here are my adjustments:
(I wasn't a fan of the fringe so I made my pieces bigger and added 2 rows of the bind off stitch all the way around the bottom edge after it was sewn together)
I used 4.50mm hook and Bernat Cotton, for the two tone I made one rectangle in variegated cotton and the the other in a complementary colour.
small(approx. size 2-4): chain 74, 15 rows of double crochet
med(size 6-8): chain 94, 20 rows " "
large(size 10-12): chain 104, 25 rows " "
when sewn together I did a double row around the bottom edge of the single crochet, chain one pattern (placing the sc in the space between the dbl crochet)
If you have any questions don't hesitate to email me.