I know this is an old thread, but I found it when I was trying to figure this out, so here's how I got it to work. I combined @boohbah method above with a script I found to enable/disable autohide automatically at
toggleTaskbarAutohide. So now I only need to have the taskbar on the side with small icons and locked.
By combining the two in a bat file which I've linked to in the startup folder (and set to start minimized), I can get my taskbar to be small on the side. Here's my bat file (assuming the toggleTaskbarAutohide is in the same folder):
toggleTaskbarAutohide /on
net stop "UxSms"
net start "UxSms"
toggleTaskbarAutohide /off