That's great news! Thanks for taking up the project (and reading my post!). I do webdev as a hobby so unfortunately I cannot contribute to the source code as I don't know enough PHP. The responsive safe zone idea is a great one to implement.
Is it possible to password-protect pages as well? I tried to do it by setting an .htaccess rule for the folder I had them in, but wasn't able to get it to work.
Then you have the .htpasswd file alongside that or in a subdirectory, which contains the username and hashed password.
If that doesn't help, make an issue on my repo and we can work it out there. Today I added password protected pages as a built-in feature, but it would need much longer in the oven before I could suggest switching an existing site over.
I've been working on my own Hotglue fork to hack in some of the features we were missing like draft pages and responsive "safe areas" like MMM.page.