Hi,
maybe I missunderstoud you but a patchbay is only a connector between different stuff. One channel of it doesn't affect the others (or else it is a BAD patchbay )
You only have one fx-loop on the Kemper but a lot of stuff you want to connect to it. You basically have two options:
1. Serial switching system.
That means that you have a switcher that activates only the unit (or units) you want to be active at a time. The rest is out of the signal chain. This is common in the "big racks" but also pretty expensive.
You could just plug everything in a row but that would give you the same effect as with too many stomp boxes
2. Parallel
This means you split the signal after the fx loop, send it through every unit seperatly and mix it together at the end.
I know the feeling of having unused stuff but I'd recommend you to choose one or two favourites and leave the rest. I use a HD 500 as midicontroller and for additional effects. And even that means a LOT of cable work, just to have these two units run together. The more stuff you connect the more likely something will fail and you'll spend your time troubleshooting.
The HD 500 has all sorts of effects and is a midicontroller. It doesn't do everything perfect (and I have the feeling it flattens the dynamics of the Kemper a bit...) but all in all its a good compromise.
I hope that helps