Hi Greg,
I’ll open a feature request for this as well but I’m not sure if it will be implemented – we are trying to not concentrate on the customizer options too much as they will be obsolete at some point in the future with the way WP is heading.
The better option now would actually be creating a block element and using the before_header hook as I demonstrated here:
https://youtu.be/1VQECQxeyQE
You can use the Container padding options to set whatever you want:
https://docs.generateblocks.com/article/container-overview/#spacing
Let me know if this helps 🙂