Density of Triangle Bag

Heavens, my wonderful SP-11 partner sent me the Bag Styles book, two days late I received a copy from Amazon. That's okay, it just means that some lucky person down the road, will receive my copy as a treat.

I love most of the bags in the book but the Triangle Bag really caught my eye. I do have some concerns that the fabric won't have the thickness that I like with it being knit with only one strand of yarn. I know the size 6 needles makes up some of it. I'm tempted to knit it using a larger needle and two strands. Has anyone tried that ? I will take Charlene's advice and double the yarn for the I-cord handles.

I plan to cast-on tonight while I'm at a breathing point in my knitting.