Digital BW, The Print

I have read through the archives and emailed Roy about this but I am 
still looking to see if there's any more advice out there.  I have a 
4000 loaded with Museum Black, 3 carbon sepia piezotones and now 3 of 
the K7 inks.  Jon Cone suggested that I could split tone between the 
warm tones (shadows/midtones) and neutral (highlights) by using 
StudioPrint.  I am attempting to do that using QTR and am wondering 
what the best method is.

I thought I would use the Museum K, the 2 darker shades of carbon 
sepia, and the lightest shade of the K7 inks to build a quadtone 
curve.  Looking at the Ink Pattern Page (at 100% ink limit), the 
lightest K7 ink is much lighter than the lightest CS ink and has a 
more limited range.  The lightest K7 has L* of 86.2 at 100% and the 
lightest CS has L* = 58.4 at 100%.  K7 at 50% = 91.3 and the CS = 
72.9.  Now I am worried that the densities of the two lightest inks 
are too different to give me a smooth transition using K7 instead of 
CS.

Is there another way to do this using the toner curves?  Or maybe 
using more than 4 of the inks to build the curve?

Any advice would be appreciated.  I am fairly new to all of this so 
please keep your explanations as simple as possible!

Thanks,
Jenny