David, I like the analysis - it appeals to me being a spectroscopist.
I have also had to look at the sensor cover plate as a source of resonance banding in the spectrum. The effect we see is very similar to that produced by an F-P etalon filter.
http://astrosurf.com/aras/fringing/opus/
http://www.astrosurf.com/aras/fringi...ter/ripple.htm
I experienced this effect while testing a high resolution spectroheliograph.
The reason for mentioning all this related testing, is to remind you that the sensor cover plates were all measured to be around 0.3 to 0.5mm think.
None were in the range you seem to calculate.
I need to double check my data files, but from memory the cover plate in the ASI 1600 is 0.5mm thick.