Finally reporting back, and my extension has been approved! After extracting out libraries into a vendor file, and splitting each view (config, live_config, and viewer) to have their own JS file, it went through! I’ve open sourced the frontend of my extension so you can see what I did. You can find it here.
I’ve also setup a simplified VueJS/Laravel Mix extension boilerplate with the same settings to give people a decent start if they’re having trouble with the intricacies of Webpack.
Cheers!