Here's another good idea I saw once: Do the internal bungee thing as usual, but use a very thick, soft foam gasket -- like 3/4" thick. To open the hatch, push down on the front of the hatch and the rear end pops up, or vice versa. Pushing down on one end lifts the other end up enough to get a finger underneath it. The drawback to this is that it'll be tougher to control the flushness of the hatch cover. If the foam is too 'squishy' or the bungees are too tight the hatch will be too sub-flush, but Don's got a good solution to that problem. Making your hatch lip might be a bit trickier, too, because you'll have to predict how much the seal will compress.

Dean