The simplest thing would be two ball bungees. Next best would be a paddle clip screwed to the hull just below the gunwale.
I bought and installed two equipment grabbers normally used by fire departments. Mine are similar to these:
http://www.batteryjunction.com/2-aex-easy-mount.html?gclid=CNHjrIieiMYCFcNafgodIjMAPA
They work great. I used nuts and bolts to attach them and had to move them once because they interfered with the tie-down straps I use to cartop my Pro-Angler. No sweat. I just squoozed a bit of Goop in the old bolt holes. Almost invisible repair.