We using the Solaris 10 containers to implement a similar idea. One container serves the public pages, while the other provides the dav. This has a few advantages like being able to run both apache servers on port 80 (different ip's, of course). Plus the pages on the public server are mounted from a loopback file system, which makes them immune from tapering since it is read only.
Obviously, this is not a solution for everyone, but since solaris 10 runs on intel and sparc, it is not too far out of reach.