I want to create a ToolBarToolBase object without adding it visibly to the toolbar. I've tried instantiating ToolBarToolBase, but I'm using wxPython version 2.8.12.1 (I can't upgrade, I'm doing this for work) so I don't think it's fully implemented. Is there any way to do this?
No. That widget is part of the toolbar. Just use a BitmapButton or a PlateButton. They both support images and would be more flexible to use anyway.
wxPython Create a LabelTool without adding it to a Toolbar