After doing some tinkering after running through your questions, I realized that Launchbox and Bigbox were both being run as Admin. I figured I would try to turn off running it as an Admin to see what happens and... that seemed to work.
The shortcut to BigBox which previously didn't work (with or without Admin) worked fine once the Admin was deselected from Launchbox.
Additionally, I also had 'bsetshell' running (unbeknownst to me from an earlier attempt) so when I did uncheck admin on both those files, bsetshell kicked in and it booted directly to BigBox on start - exactly what I wanted (thank you @lordmonkus).
I will happily admit that my lack of knowledge in the Windows space added to some of the confusion. Thank you all for your help with this. After spending hours tweaking Launchbox, to have this last piece haunt me for hours and days was really getting to me! Now I'm reaching the point of being crazy proud to show off what I have. Again, thank you all & Launchbox team!
EDIT: Spoke too soon. Everything looked like it was up and running, but when I actually went to play a game BigBox threw up "An error occurred while trying to launch the game: The requested operation requires elevation."
I selected BigBox only to run as admin and that allowed me to play the game. However, in doing so, I lost my ability to load BigBox via the \Programs\Start menu as a shortcut. Which - I believe - brings me full circle to my original problem. THAT SAID... I now understand how to make bsetshell work, and it will give me the setup I want. Getting back to the Windows finder is a hassle if I want to tweak something, but it is doable. Given what I know, I am not thrilled, but happy with this current solution.