What seems best is to use clams for bait. Then find eelgrass and put the traps on the edges, but put them just far enough away from the grass such that when the tide starts pushing grass it can't clog up your trap. Ideally, the tide pulls the scent of your bait through the grass, then after the shift the grass lays over the other way. Guess just kind of depends what side of the grass you set on for the tide.