One could have mod_proxy compiled in and dispense with the duplicate ProxyPass/ProxyPassReverse directives (necessitated by the way redirects are handled by ProxyPass). mod_rewrite allows us to say, for instance,

RewriteRule /cgi-bin/ http://cgiserver.example.com/cgi-bin/ [P,L]

The P flag tells mod_rewrite to pass through the request.
One can also use mod_rewrite to pass through requests to a multiplicity of back end but similarly functioning machines. One could use this:

RewriteMap    lb      rnd:/path/to/backend.table
RewriteRule   ^/(.+)$ http://${lb:www}/$1           [P,L]

to pass requests to back end servers in a random fashion where the backend.table consists of

www ww1.example.com|ww2.example.com|ww3.example.com|ww4.example.com