Outside of the Kemper I have actually made progress.
Back in 2014 I paid a really good guitar tech to mod 2 of my guitars with Roland GK-KIT-GT3, a PRS S2 (1st gen, main guitar for last 10yrs) and PRS SE 24.
Early last year my band 40 Day Warning lost our bassist and we couldn't seem to find a replacement, so, I dug out my Boss GP10 and made a custom patch for bass. By default the E string is always on, then, pedal 1 is E+A and pedal 2 is E+A+D. I press the pedal depending on bass strings needed.
In the last quarter of last year I then got the Boss SY1000, which seems to respond better (less latency?), again using a custom preset to manipulate the strings on/off.
This is then run into a Fender Rumble Stage 800 amp.
The guitar side is it's own thing, digital modeller into JCM2000 TSL 122 power amp.