wrote:
Not just one, but at least two! There's the big red barn which is just down
the road (west) a bit from Theater in the Woods, then one about another half
mile or so farther.

The Red Barn down by the Ultralight area?
That was where the airport's southern boundary was until 1988.
Immediately following Oshkosh, work began on the 1000 foot runway
extension to allow Concorde more runway for landing and takeoffs.