IKO, webgateways and the DirectoryIndex

Good morning dear community,

This is like my first post in this community. Let's see how this turns out.
I have a question about the Intersystems Kubernetes Operator and the deployment of the webgateways.

I am responsible for the hosting and deployment of the apps. For the future we are planning to host our application in a kubernetes cluster. I am using the IKO for this.
I am using webgateways, for external access as separate pods. And sidecar containers for internal access, like the management portal.

My current Problem is the configuration of the webgateways. Our application is hosted on /csp/reise/, but I specifically need to specify our index.csp, to access the application /csp/reise/index.csp

Of course, this is not very pretty.

I have already set the DirectoryIndex to index.csp and even /csp/reise/index.csp, but when I access /csp/reise and /csp/reise/.
I get an error 404 on both urls.
But I am able to access /csp/reise/index.csp

This is my current CSP.conf, which is just the basic autogenerated configuration, but I added the RedirectMatch and DirectoryIndex.

    CSPModulePath "${ISC_PACKAGE_INSTALLDIR}/bin/"
    CSPConfigPath "${ISC_PACKAGE_INSTALLDIR}/bin/"

    RedirectMatch ^/$ /csp/reise/
    DirectoryIndex index.csp index.html

    <Location "/csp/reise">
        CSP On
        SetHandler csp-handler-sa
    </Location>

    <Directory "${ISC_PACKAGE_INSTALLDIR}/bin">
    AllowOverride None
    Options None
    Require all granted
    <FilesMatch "\.(log|ini|pid|exe)$">
        Require all denied
    </FilesMatch>
    </Directory>

My suspicion is, that the apache server expects an existing file, for the DirectoryIndex to be functional.
But since this just forwards the request, apache can't handle this.

I am thinking if the webgateway would be better suited with nginx, or if my ingress controller could handle the incoming traffic.

Am I missing something? Is this just not possible to achieve?

Thank you for your help.