The ziplocks will work well. One way that was discussed here a while back is to get a piece of cloth and sew the end so that a piece of conduit can be inserted. Weight down the opposite edge of the cloth behind the wing and drape it over the wing with the wing aligned with the edge of the bench. Let the conduit side hang down. I haven't tried that but I will next time I fully sheet a wing. I think it should give real even pressure over the whole wing.