We build is a CMS platform for dynamic website with content addition. Just small update in text, Another test update
What I mean is, if you're going to match against ANY segment, this means that you cannot use any controller at all (which is, by default, the first URI segment), since the router will always re-route you using your defined law. In order to allow CI to execute other controllers (whatever they are, I just used some common web pages, but can be literally everything), you need to allow them by excluding them from the re-routing. And you can achieve this by placing them before your ANY rule, so that everytime CI passed through your routing rules it parses first the one you "escaped", and ONLY if they don't match anything it found on the URL, it passes on to the :ANY rule.
I know that this is a code verbosity nonetheless, but they'll surely be less than 6K as you said. Since I don't know the actual structure of your URLs and of your web application, it's the only solution that comes to my mind. If you provide further information, such as how are shaped the regular urls of your app, then I can update my answer
What I mean is, if you're going to match against ANY segment, this means that you cannot use any controller at all (which is, by default, the first URI segment), since the router will always re-route you using your defined law. In order to allow CI to execute other controllers (whatever they are, I just used some common web pages, but can be literally everything), you need to allow them by excluding them from the re-routing. And you can achieve this by placing them before your ANY rule, so that everytime CI passed through your routing rules it parses first the one you "escaped", and ONLY if they don't match anything it found on the URL, it passes on to the :ANY rule.
I know that this is a code verbosity nonetheless, but they'll surely be less than 6K as you said. Since I don't know the actual structure of your URLs and of your web application, it's the only solution that comes to my mind. If you provide further information, such as how are shaped the regular urls of your app, then I can update my answer