[argyllcms] printtarg -k options advice

Hello, I am working on profiling an uncoated paper that exhibits a lot of ink spreading and has a TIL between 180-220. The printer is an inkjet with multiple light inks. I have very carefully limited ink in multiple ways. My Ergosoft RIP even allows control / "ink limiting" of the light inks by specifying the blend patterns, as well as the specific droplet sizes allowed out of the head. My printer is a aqueous dye based C, M, Lc, Lm, Y, K, K1, K2. I think I'm using the minimum amount of acceptable ink. I have also carefully linearized through the RIP.
My problem is neutral rendering along gray axis between 60% and 80% densities and also the coloration at maximum density. Unacceptable color banding is occurring in the 60%-80% range due to abrupt transitions of the C,M Y curves as colprof is trying to stay within my ink limiting specifications. I am running out of ink limit and black generation combinations to try, so I thought of giving the Spectroscan some easier material to read by playing with the black generation in printtarg. Am I correct in thinking that the -k option does this? If so, are there more descriptions for -kg, -kc, -ks and -kn? And, do they accept numerical values to refine their effects?
The only software to give me reasonable results on this tricky paper was on old version of PrintOpen (3.0). Maybe it was doing a lot of smoothing, and is that an approach I should try next? 

Here is one of the better attempts out of many I've tried:

targen -v -d4 -g128 -f4712 -l210  500SV1440bAG308
printtarg -v -iSS -h -t300 -C -pA4R 500SV1440bAG308
chartread -v -c1 500SV1440bAG308
colprof -v -qh -kp 0 .24 .99 .995 .78 -L100 -r1 -cmt -dpp 500SV1440bAG308 

Any thought?

Best regards,
Mike

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