> Unfortunately, there isn't yet a public example of an extension that hooks into Site Settings
Just from the description you provided, it is still not clear enough for me to say much about it.
The general concern with putting it into SMW is that this forces the people working on SMW to hold it into account. This means making sure it does not get broken when changes are made on the master branch. That is hard to do since it requires the Site Settings extension. If the code is really trivial, then perhaps this is fine.