The curve will definitely give you troubles with the forward hatch, plus, these look a bit clunky for such small light hatches.  I drill-fill-drilled two holes thru each cover and ran a loop of line, knotted below.  they are soft and leakage does not seem to be a problem.  Last weekend I participated in some assisted rescue and self-rescue training.  the boat (Shearwater 17 H) spent a good amount of time upside down.  I got about a cup of water in the bow and none in the stern.  My gaskets by the way are CLC standard and the hatches have invisible bungie hold-dowms.

An added advantage of the loop pull rings is that they are a good place to run safety lines to secure your covers when cartoping.  Just completed 3,000 miles accident free.

Paul

Thanks, Paul.

For what it's worth, you can get these as small as 1.5" diameter, so they don't look out of scale. You could run your safety line thru the rings, too. I could double up the forward hatch where the pull would go to get the required thickness.

They rattle.