mod_rewrite not working with reverse proxy in vhost - apache

Question

All I am trying to do is:
rewrite /static/styles/min.css to /static/styles/min.css.gz
rewrite /static/scripts/min.js to /static/scripts/min.js.gz
The trick is that those files are on a remote (public) server which I'm reverse proxying to.
I am doing this so I can workaround the same-origin issue with our javascript, and to speed up delivery in general. The .gz files already exist.
No matter what I do, I cannot request the .js file and have the .gz file returned.
I have tried this with numerous different RewriteConds to no avail.
I have also tried it with RequestHeader unset Accept-Encoding enabled, and commented out.
Google PageSpeed keeps telling me that it is not receiving the compressed versions, and when I request using curl and manually setting the "Accept-Encoding: gzip, deflate" header, I continue to receive the non-compressed versions. I cannot put the rewrites in the .htaccess file because the reverse proxy is processed before the .htaccess, and I need the rewrite to already be in effect when the reverse proxy happens. I'm at a total loss.
Here is my non-production setup (I know it needs securing):
<VirtualHost *:80>
ServerName ww.test.com
DocumentRoot "/htdocs/public"
Options +MultiViews
AddEncoding x-gzip .gz
AddEncoding gzip .gz
RewriteEngine on
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteRule ^\.js$ $1\.js\.gz [L]
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteRule ^\.css$ $1\.css\.gz [L]
<FilesMatch .*\.css\.gz>
ForceType text/css
Header append Content-Encoding gzip
</FilesMatch>
<FilesMatch .*\.js\.gz>
ForceType text/javascript
Header append Content-Encoding gzip
</FilesMatch>
ProxyRequests off
ProxyPass /static/ http://www.ourCDN.com/ourAccount/environmentName/
<Location /static/>
ProxyPassReverse /
#RequestHeader unset Accept-Encoding
</Location>
<Directory />
Options FollowSymLinks
AllowOverride All
Order deny,allow
</Directory>
</VirtualHost>

Answer 1

FilesMatch rules apply only to files on disk - a proxied request isn't a file on disk and therefore won't be captured by a FilesMatch rule.
You probably want
<LocationMatch "^/static/.*\.css\.gz$">
ProxyPassReverse /
....
</LocationMatch>