Default Site

Is there a way to set a Default Site for SDP, so that all new requests, service requests, changes, etc, will always point to the default one, and not the "Not associated to any site?" I tried to create a business rule to allow all created requests to set the site to "Our site name" but that is not an option either.

We originally were configured with the "Not associated to any site" as we had no sites configured. However, I noticed that if you want all Requesters to view all requests, you could choose to see only their requests, their department requests, or their site. So we had to define one site to use; we do not want/need more than one site. Also, can the Site field in the request template be not listed, or at least not an editable field that the Requester can modify?