You're correct about varying white balance levels and needing to adjust from night to night and object to object.
I usually broadcast at
https://www.nightskiesnetwork.com/ as do many others that use one shot color (OSC) cameras. Some use the red and blue color sliders to get a rough color balance while I leave mine at the default of 50/50 for R/B. Both process will deliver similar results with the adjusted R/B tends to give a better white balance.
Most of the guys that adjust the R/B will setup their system with LPS filters and get a general setting for R/B. Usually since most are using an LPS filter this tends to severely limit the red channel so their setting for red will usually be 99. This usually doesn't perfectly line up the red histogram curve with the green and blue but gets close. Then you'll adjust the blue channel and there is usually enough headroom to get almost perfect alignment with the green channel. While making these adjustments make sure you have the smart histogram open and watch the red, green and blue mean readout and try to match this as close as possible. You'll need to get the best settings based on your skies and equipment.
Once you have your base line for red and blue color balance you can create your dark library. I would setup multiple exposure and gain settings and shoot 10-20 subs to make the master dark. Make sure you are using the same R/B and brightness settings that you intend to use for Live Stacking.
Once you start Live Stacking with your R/B and brightness adjusted master dark applied the histogram becomes live once you have 2 frames stacked click the auto stretch and auto white balance you should see a fairly color balanced and corrected stacked frame displayed.
My process is just as above except I leave the R/B at 50 and make all the color adjustments in the Live Stack histogram. I use the red, green and blue vertical sliders to align the peak for each curve.
I tend to use the same master dark library for several months and will usually create new masters darks as I notice new hot pixels. If you're using a cooled 294 that's another advantage since you'll be able to control your temp and have consistent thermal noise.
My settings for my rig RC6 f/9 1370 FL IDAS D1 LPS filter and ASI294 MC Pro cooled to -15c (I'm able to maintain this temp year round)
Brightness: 4
Red: 50
Blue: 50
usually use gain of 300 and exposure of 15, 30 and 60 sec
create new flat nightly once I've fine tuned focus for the night.
Hope this helps!
