I don't know much about the limitations of LMS running on a NAS, so let's get that forewarning out of the way.
Whitebear makes your SBs look like normal DLNA renderers, and acts as a DLNA server, brokering requests to LMS. That means, any suitable controller should be able to stream music to your SBs.
There are some advantages when Whitebear runs on the same system as MC, when MC and LMS share the same set of files. It can ask LMS to directly play the audio file - after it brokers the play request, it is not involved and LMS is doing the playback. Otherwise, MC will stream the audio file, either transcoded or native, as supported by the renderer.
So the anwser to your question is Yes, MC can run on another system, and you can push the audio stream through Whitebear to LMS.