I find the Suspenz to be pretty rugged.  I use one cam strap each side, and don't go across canoe, just to thwarts front and back. Can't roll and friction seems to keep it from moving aftward or sternward. 
I looked at homemade but they get awkward to portage when they can't be used.
				
			I looked at homemade but they get awkward to portage when they can't be used.
	