As pictures are easier, I've quickly drawn my plan.

I emailed Targus as well and they said it would work. They did say the host charging will stop working, ie have to charge the laptop separately. That's fine.
The problem with a KVM I believe is that my laptop only has a single USB out, and thus not support for 2 monitors; this is what the docking station enables me to do. There are KVM's with docking station enabled, but couldn't find them.
All very complicated to be honest! I was surprised my docking station works out of the box with my desktop.