Image Fullpath
please allow full url path in config.inc.php $phpwcms['file_path'] = 'filearchive'; so as an example this would be possible https://cdn.example.com/f89a612759e57d925b9e0defdef3b6d2.jpg
It's a more difficult demand because in general it would be necessary to implement storing uploaded files on CDN storage too. I have to think about how this could be done…
for me this question is more server related then phpwcms. it is easy to splitt or mirror parts of webspace to other systems via symlink or something like that.
another good solution could be to use subdomains to get a lot of files from same webspace without reaching browser max. connections per url (=magento solution).
Regarding upload to CDN... Something like this could help https://github.com/thephpleague/flysystem