[samet]

I went through the very same path and wrote almost the same Bash script, then packaged it as a MacOS app:

http://github.com/samet/sessionless

When I need a true sessionless browsing experience, here is what I do:

1. cmd+space, open Sessionless

2. do whatever do you want with a true sessionless mode

3. cmd+q, quit with sweeping every trace

4. profit

Besides, I can open more than one independent Sessionless windows; a feature which is not possible using Incognito mode.