As a test, I set up a local tomcat with two webapps directories.
In server.xml, at the very end, is a stanza like this:

<Host name="localhost"  appBase="webapps"
   unpackWARs="true" autoDeploy="true"
   xmlValidation="false" xmlNamespaceAware="false">
</Host>

If you add another one, with a different name (e.g. name="something.else.com") you can deploy webapps from all over the place. This could be useful when you want to set up a complete Cocoon in a homedir, and not on the server's local disk, as we're doing with mariage v4. I successfully added a webapps directory that was in a folder in my SAN homedir that had been mounted over samba.

Hopefully this means that we can do the same on the web servers. The only issue that might come up is those pesky apachsrv permissions. Not sure how best tot deal with those...