Dolly/steep shore issue

I'm looking for advice on securing my Sunfish to my Seitech dolly. I now use a strap from a Yakima rack system to hold the boat in place, but it's awkward, grabbing the strap from one side, walking around to the other side, threading the strap through the loop and tightening it, often with the waves bouncing the boat around. There has to be a simpler way. Ideas?