Having come to Backdrop from Drupal 6,7 and 8, and having developed scripts to quickly create a Drupal 8 site and upgrade using Composer when required, then push/pull to Dev and Production. I decided to do the same for Backdrop using the 'Versioned staging directory' method. I have put the whole lot on GitHub if anyone is interested here.
My system will create a Backdrop site in under three minutes. Makes it easy to clone sites and also upgrade Core.
I have found that it helps me avoid making mistakes. I hope I am not stepping out of line by talking about it on the Forum, but someone might like to use it or adapt it somehow.
I am aware the actual scripting might not be the most elegant, but it does work.
I welcome any feedback.