OK, thanks for the replies on the FG-21, folks. I'm leaning toward using the metal Saito mount - just cringing at adding a bunch of extra wood/epoxy on the firewall to get to the correct distance
Has anyone else had trouble with the holes for the wing bolts lining up properly? It seems like the left side on mine is quite a bit off, despite having the wing lined up flush with the fuselage lip at the trailing edge of the wing. I'd post a photo of it, but I don't have enough posts yet to add any attachments.