Multi-Site NodeJS extension

Hello.

I know that NodeJs does not support multi-site setups and you have to launch a separate instance for each site.

It does not look friendly and will require a lot of manual work with configuration, managing, monitoring, etc.

As far as I understand it is possible to alter available routes and replace them with my own handlers, so it should be generally possible to create a handler that will override config settings before launching actual handler and then change them back.

Could someone share ideas about how to write an extension, that will allow to override backend details based on the requester domain/some header/etc.?
If there is at least a general vision of how it can be done or some example, it will be really appreciated.

The only difference between sites will be the backend domain details, so when a client connects using some site, it will send messages to the used domain, not the domain defined in the configuration.

Thanks in advance.