We run a SaaS (software as a service) company where we allow multiple clients to create "sites" within our application.
This typically results in the client having a site that is a subdomain of our main domain. eg: someclient.mybusiness.com
We support SSL for checkout, and have a single wildcard certificate so that all clients are covered (since they are all on *.mybusiness.com)
We now want to begin offering custom domain names. In this case, the clients would still have their site as someclient.mybusiness.com, but could go to their hosting provider and create a CNAME pointing to someclient.mybusiness.com. So as a result, they could have buystuff.clientsite.com pointing to someclient.mybusiness.com.
My question is how best to go about supporting SSL for those clients that want to use the custom domain option?
I've read about SAN, but I'm not sure how that would work with our existing wildcard cert.
I've also read about SNI, but that would require that our clients purchase their own certs, which our marketing department would prefer to not be the case.
Any thoughts on this are greatly appreciated!