Thanks for your reply! I'm not actually using Tee-Wee, but VS Code. That said, I was able to ask in the Twine discord and found out that there's a command line option for Tweego (the command line twee file compiler) that is "-t" (for "test") and that worked!
Your comment, even though it's specific to Tee-Wee, got me on the hunt for being able to use something other than Twine itself to see the debugging Backstage sidebar when testing my Chapbook game, so thanks again...