Pilot DAR,
As you mentioned it, I had to check Vso for the Cessna I had in mind - 172R. Vso is 33 kts. Then I checked the 172S. Vso is 40 kts. I thought it was the same airframe with a slightly higher power engine and climb optimised propeller?
As for the rest I am humble to your experience in flight testing. My suggestion of slowing below best glide to steepen the approach angle was not to maintain it until flare. Rather to realise that energy management by speed is another tool in the toolbox. Use it until back on profile, until you've got the right picture back. I have seen some pretty scary forward slips as the pilot doesn't lower the nose to match the increased drag. That manoeuvre in itself introduces some risks.