Hi Kevin,
The "sharp" lip is a 1/2" wide strip I cut off a full sheet of almost veneer thin 1/16" ply.It was easy to do.Because of no pocket for the gasket to allow for penetration the packers are needed.I like the packers anyway 'cause it beefs up the hatch rim so it can be thrown around a bit when being used on my little expeditions.I just hope this lip is not too vulnerable as it is right where you'd knock it pulling out your cooking gas bottle or whatever.Here is another view.
cheers,