That’s a great find, thanks for posting. It is amazing what wartime subjects make in onto such ‘light’ programming these days.
The plans shown didn’t look like decoy plans to me, more like balsa-wood model plans but I could be wrong. The wartime decoy wouldn’t have had the box underneath (not sure why they built it that way) as the shadows a decoy cast, including the undercarriage, were as important as the general look of it.
I doubt there was much of the decoy worth saving; unless you were interested in it as a decoy. It looked very shoddily covered and wouldn’t last long in any sort of weather.
To get it to sit on an undercarriage would require a spar which would make it more complex and expensive. It was cheaper sat on the box. Your right, it would only be skip fodder.
Proved the point though, nice to see