At 37"x18"x27" folded this won't fit our largest canoe portage pack.  It's even too big for a 
55 gallon trash bag  (35"W x 55"H).  Looks like a 
95 gallon trash bag will do it (61"Wx68"H), with enough left over for a good waterproof roll closure.
This bags are 1.2-1.5Mil thick, but can still be punctured on a rafting trip.  Replacement bags and duct tape might do it for ypu.  I'd suggest taking pedals off to minimize bag damage.
Good luck.