<Preface: Yes, I've already spent all night googling this.>

I tried to get used to using Blender "lefthanded" as I call it, using the default Right click for selection, but I have to work on several systems throughout the course of the day, and it's just not ergonomic for me to switch primary use fingers all the time.

So I switched blender to use Left mouse for selection.

But this causes a headache in that when I do Weight Painting, I cannot select a bone because the Left Mouse is already bound to painting.

Is there a way to add in functionality for selection, as though it were another button? For example binding "Select" to the spacebar AND the mouse cursor? Or a way to select a bone in Weight Paint mode without using the select button?