Using the approach that you suggest will definitely clip the highlights in the final image when one uses Curve Calculator.
Based on this test, choosing color G255R154 is the wrong choice. And choosing the color from the tonal palette printing is the wrong approach with PDN.
After looking at the test some more it appears that that the cyanotype is a bit longer scale than would probably be obtained (possibly due to the light source spectrum and long printing time). As a result I would suggest to Dave that since he is using the 2200 printer to increase the ink density by about 10% in the Epson driver and reprint the CDRP and then reprint it to obtain a new SCD (Standard Color Density or blocking color). Then reprint the Tonal Palette again with that fill color. If that doesn't work then increase the percentage some more.
I recently had to do something similar this summer when calibrating for Kallitype on a very "fast" BL UV printer. There was almost no white patches in any of the color paths shown in the CDRP print and one of the paths had some tonal inversion. In that instance I finally had to make a 20% increase in ink deposition. Once I did that everything 'clicked'
Actually I have several CDRPs already printed for use as work arounds for such problems and it's probably not a bad idea for other PDN users if their driver allows.
Perhaps Mark's documentation should be expanded for these kind of situations but on the other hand this might lead to confusion for beginners. That's why Mark has established a private Yahoo group for PDN users (much like Gene Laughter does with his Yahoo bromoil group - established for students of his workshops).
The first printing of the Tonal Palette is printed without a curve, it serves as the source of data for generating an adjustment curve in Curve Calculator, therefore it needs to be full scale. The tonal palette is not inverted so it is a 'negative'. Not counter-intuitive if you read the documentation or RTFM as they say.

Not that I'm suggesting that Dave or anyone else didn't or doesn't, that's just the way Mark set up his system.
Hope this clears up some mysteries,
Don