We do exactly this, we create one per tenant. But since this is multi tenant, there’s multiple servers.
We provision a subdomain for each tenant which is used by our SIP and HTTP proxies to determine different routing and security rules.
Additionally, clientname.pbx.com sounds stupid, but you’d be surprised how much it improves customer satisfaction when customers see their company name in the URL when logging in! That’s why I asked numerous times to make VitXi works with any subdomain.