Hi mlombard,
if you are looking at a studio way of doing this, then you could take advance of the functionality in Admin which allows you setting up a different skin for a certain node. What you could do is to create a sandbox category (or more than one) and have the new skin assigned to that node and all of it subnodes.
In this way you / others with appropriate access should be able to edit the CSS and the wrapper (along with the other skin properties) without interfering with the main community. It is also possible to hide the "sandbox category" from the standard hierarchy and navigation so it does not even appear there.
Thanks,
