It would be great for customers to be able to request a new SDDC from VMC portal or to ask to add more hosts (over the limitation of resources)
As far as I understand, there is not an official process to create a second SDDC or to add a host beyond the limitation.
Having an interface where you can query a new SDDC deployment in new Region in the VMC Portal may be a good idea a specially if it triggers a workflow to speed up the request of the customer.