You can hide them, using the options available in the master track menu button, but it won't reduce the minimal mixer height : all you'll see will be a 'blank' area above the mcp panel.
So, indeed, you can try to reduce the
mcp_min_height value, going down to about 210, but don't expect any display of an eventual track icon, with such values.
At the end, it would indeed probably be more relevent to accept that track icons could be left out in such a case. Think I'm for another update...
CORRECTION : after few more tests, a more fiable
mcp_min_height value is something around 230, as there's the need to take account of the mcp track panels vertical jump when the mixer window width is under the sum of all the tracks ones. Hope this will help...