Not exactly sure if this will work in your situation, but hiding where you are redirecting to is normaly easily done using [L,P] instead of [R], telling mod_rewrite to proxy the request (you need mod_proxy as well, but they both should be present in a n apache-installation).
Additionaly ProxyPassReverse statements may be necessary if your script issues redirects, letting the proxying apache rewriting given urls on the fly before passing the redirect through to the client.

Additionaly you should check if the available CPAN modules (e.g. Apache::ProxyRewrite) could do the job better, if mod_perl is present.

regards,
tomte

Hlade's Law:

If you have a difficult task, give it to a lazy person --
they will find an easier way to do it.