"However, I also don’t like to carry two computers just to jot down personal notes. My remedy is to install a virtualization system and create a “personal” virtual machine."

I have the same problem, but I'm not sure if a VM is a good solution. The work OS has full access to the VM and I don't trust putting my personal things even in the VM. (I consider the work laptop backdoored and full with spyware.)

Why bother with a VM? When I'm in that situation, I just run my stuff in the cloud and ssh to my machine, alternatively, ssh to my machine at home. Much more minimalist and light weight than a VM as long as your customer allows outgoing ssh and/or connections to a tor/i2p hidden service.

If I'm just jotting down personal notes, I use a pen and a notepad. If I need to transcribe anything into my long-term notes, then I can do that at the end of the day/week/whatever, when I review what I wrote down.