Hi Damian,
We do have several approaches to publishing the same content on multiple pages.
Global content is one solution.
ModuleWrapper is probably closer to what you are looking for and it works with the Html Content feature though it isn't the most recommended thing and it doesn't solve your need for a custom feature and permissions may not work as you would like when using ModuleWrapper.
If you need to extend the Html Content feature, cloning it is the only recommended way.
Best,
Joe