How to Copy an Upfront Builder Theme?

Hello,

I would like to begin using your new Upfront Builder functionality to its fullest extent. For me, this begins with making a Boilerplate theme that I will modify for future themes. Beyond that, I would like to make general categories of sites/themes that I will then modify further yet.

To do this, I need to be able to copy themes on the same site. The problem I encounter is that the "theme directory" is not a modifiable option and, for obvious reasons, must be unique. I took a shot at it by unzipping the theme, changing the first level of the folder to match my new directory.

This was successful in allowing me to upload the copied theme into its unique directory, but I am unable to edit it. I simply get a 404 for the "create_new/boilerplate" URL. This is a rewritten link, meaning that I'm a little over my head to troll through all of the Builder files to find where this is defined.

I would love to know what I can do to copy Builder themes. By far the biggest use of my time is setting the fonts/colors/global CSS, so this will be an amazing leap forward for me as well as all of your other professional clients.

Thank you!
Jeremy