yeh - scale comparisons - not much real use for developing a good model tho - as you noted -
The 20 lbs end weight for 24 sq ft of wing -- seemed a bit optomistic for a wing with any ability to handle more than a few G's.
I built some minimum structures long ago - just to see -- and lost a few models due to folded panels -- found out real fast that structural requirements really ramp up quickly as size increases.
far more critical than the airfoils for our models .