I forget about alt process people...sorry. My comments are directed mostly at conventional enlarged silver printing.
My comment about adding 10% is to point out that the image stain is proportional to the silver image, so that for a given process, there is some factor that can be added to make a simple densitometer work w/o a blue or UV channel.
For you alt process folks, I will try to run a PMK negative through the spectrometer soon. What is you spectrum of interest?