This is tricky. Historically this wasn't possible since SSL didn't permit indicating which virtual host it was attempting to access as it sets up the connection to the designated IP address. This has changed somewhat with Server Name Indication (RFC 4366), a feature of TLS.
Apache has taken a long time to get support for it, but it now does. Your version is new enough it should support it, but you'll need a browser that also does. Before working on the rewrite stuff, I'd start working on making sure that https://server1.example.com/
https://server1.example.com/ returns the right VHost. Once it does that, the ModRewriteMod-rewrite stuff should just work.