Randy, Phil, etc.,
There is more history to that method....
The first GSCB OTS meet was October 1970, I was one of the entrants.. ( 1st.. Bob Hunt, Veco Mustang; 2nd John D'Ottavio, All American Sr; 3rd yours truly, Barnstormer) That is one of the few trophies that I have kept over the years.
I CD'd the second OTS contest in the country the summer of 1971 at Buder Park, St, Louis.
****John Davis quick built an All American Sr for the St. Louis contest and took 1st.
His All American Sr had a foam wing with the "kept foam" method that was "created" many years later! ****
I am sure that only two of us saw that airplane before it was covered. At that time, any entry for the brand new event was most welcome, as long as dimensions were true.
I would not be surprised to hear that somepne might have even done it before then.