I have a suggestion for this new sidebar.
Add a tab system at the bottom. So you can switch between the documentation sidebar and the normal sidebar. Saves you having to wait for the page to load. I would think of it as:
[documentation][forum/general][admin menu?]
[filter]
[guides]
[theme/customization]
A lot like the suggestion I made for the admin sidebar.
If you are a moderator, a third tab can be in there as well for even faster navigation.