Digital BW, The Print

Hi all,

For a number of reasons, I'm going to be producing a large quantity of
B&W prints at Winkflash (obviously these are not fine art prints).
I've printed several test prints, including a 21-step and 51-step
wedge. Surprisingly, the photo printer(s) are very well behaved. I
plotted the density curves and their shape and smoothness rivals
linearized output from my in-house printers, except for the shadows
where things start to block up in the 92-100% range.

So here's the challenge...I obviously don't have control over the
Winkflash printers and they don't allow for embedded profiles either.
They assume sRGB and disregard any profile. My plan is just to create
a B&W ICC profile for soft proofing (using QTR-Create-ICC) and make my
Photoshop corrections specific to that soft proof. 

Does making tonal corrections that are device dependent when you don't
control the printer (and can't embed a profile) seem like a good
approach? Is there a better way? 

Also, I have an X-Rite 810 densitometer, not a specto. Can
QTR-Create-ICC be made to work with just density data?

Thanks for any suggestions.
Peter.