Sounds about right Brett. I wonder if the guy that did the STC spun it enough to tell the difference...he took the slots off. To me the slots seem too far outboard, not in front of much aileron. With the forward tank, it seems to be a little nose-heavy and I bet that helped more then anything.
I just noticed yeaterday that the Columbus airplane has changed hands in the FAA registry. I hope they don't take it down. I go out of my way to look at it every time I am in CMH.
I have an old B&W picture of #101 the "first" Culver you mention when it crashed. I think it lost power and on landing, slid to a stop in a ditch, jamed under a small bridge. It got dubbed "The Culvert Cadet"...
I'll get a copy of it to Bill to post sometime.