Thanks folks
A little more progress on the interior....

Ideally I would have entirely removed the area where the lower wing joins the fuselage, but with the surgery done in that area I think the fuselage sides would be too weak, so I've just thinned it down. This does mean that there is a step up, instead of down, from the observer's floor to the "fabric" under the pilot's cockpit, but I'll live with that.
I can now make a start on the fuselage cross members and some of the smaller detail items....
Ian