It wasn't a problem for us this summer. We drove from Southern IL. to Black River Falls, WI. without any problems. (Except for the hunk of rubber that bounced up off of the road from a semi, into the canoe and then back down through my sunroof on the way back home.) I used ratchet straps at the mid-section and tied off the nose to my pushbar that I got from Tone. No worries!
I'd post a picture, but I seem to be having trouble with that for some reason.