I did some of the engineering for the Skylane STC back in the late '60s.  Also flew the 170B version.  The original was a modification of some Aeronca model, then tested on a Taylorcraft BC-12D in the mid-50s.  At the foothills of the Allegheny mountains, we had some distinctly unpleasant turbulence.  The modified struts and wing hinge pivots made flying an order-of-magnitude better, as well as improving lateral stability.  I flew many flutter tests without any problems whatsoever.

Unfortunately general aviation is no longer viable or fun, but they were truly golden years back then.  I don't have any of the documentation for the STC, but have a lot of good memories of how it was done.