The new sheet wing on my GLH is only about 64 sq/in and it glides fine. The built up wing was a piece of cake to land. If I ever get the time I think I'll do another built up one as I think I can get lighter still. I just really have to be in the right mood to mess with toothpicks that size. Once you get below 1/4" thick it gets tough. I just cut twice as many ribs as I needed as I broke half of them building it.
I have one of the aluminum backplates from e-bay (ridenfligh) and it works well and saves running new holes if the firewall was setup already. I have learned that you need to bolt the engines on at this size, not screws, to get past the vibration barrier.