-- Last Updated: Nov-17-12 7:56 PM EST --
I have put behind the seat, and usually attach it to the seat. I think mine is smaller than the 13. Of course, the seat needs to be reasonably secure if you are going to do this.
But usually when I am touring and carrying gear, I am more conservative in my paddling. So only rarely rolling.
I did roll a year and a half ago when I was doing an overnight rock gardening trip on the Big Sur coast, but can't remember if I had a dromedary there. Was in my Alchemy (14'), so likely did, as there isn't a lot of space elsewhere. But if it fit, I may have had it at the bottom of the day hatch.