Supply different CDN hosts for HTTPS

My CDN gives me my own subdomain for normal http traffic on http://cdn.mysite.example.com, but for SSL they give me https://secure.example.com/mysite. So changing the http to https wouldn't work 100% for me.

I was thinking of providing an additional text box under the check box for enabling https that functions exactly like the CDN Mapping text box. If HTTPS is turned on and this is a secure page, the code will look at this text box instead.