Thank you for the super fast and helpful response, I modified STMoutline.cginc as you suggested and it worked! And yeah I feel like this is the functionality most people would want with textures and outlines, so making it the default behavior or an option at least seems like a good idea to me.
As for the fading stuff, yeah originally I was going to try to use Unity's animation stuff to fade the text, but after I discovered the "All At Once" option and Unread(), I was able to use those to achieve the effect I wanted to. So for me, fading works fine as it is now!