Another extension here, it’s pretty closely related so rather than make a new topic I’m posting it here. This adds an action that visually appears to show/hide all docker title bars. More pixels reclaimed 
“Toggle Docker Titlebars”.
It is enabled once when a view is created with a 1.5 second delay, but I imagine it could also be triggered before when the main window is created (swap out viewCreated for windowCreated). Make sure your workspace is saved before trying this out 
Floating dockers will be re-docked, as I said before I don’t use them so it doesn’t bother me right now. I’m sure there is also a way to, in that it seems to just re-dock them for whatever reason. The idea is from various posts in the forum, I don’t have any saved but I think there are a few scripts here and there that do similar things.
While adding the action to my toolbar I found there was another action named very similarly, I thought it was a bug or some plugin I downloaded added this extra action. It’s called Show Docker Titles (in settings category in keyboard shortcuts) which doesn’t hide the title bars entirely, just makes it blank, so no lock button, title, or window/close buttons, I didn’t check if it works with floating dockers.