How to use Proxy to avoid cors error

Summary:

When I try to call a Rest Service in Visual Builder i get a CORS error.
I can't add to the white list on the Target server.
So i want to use a Proxy.
When I define a Backend in Visual Builder I can only see only see the proxy option when i check the "Local Server Definition" box.
Local Servers definitins can't be published.

How can I use a proxy for a rest call?

Version (include the version you are using, if applicable):

Oracle Fusion Cloud-Anwendungen26A (11.13.26.01.0)