Z coupler internal routing

Hello hello.
I’m currently designing a travel frame with a Z coupler on the downtube. I’ve seen lots of examples of similar frames with internally routed hydraulic lines with a hydraulic line coupler. Lots of these frames use electroinc shifting to dispense with the need of splitting the gear line, although I don’t want to use electronic shifting. Some have an externally routed rear gear line with a splitter. I’ve been scratching my head wondering if there was a clever way of doing an internally routed rear gear line (for 1x) instead with a cable splitter where the Z coupler is?
I’m quite happy to use external routing if it an impossibility, but was wondering if anyone had any innovative ideas?
Thanks a lot.

Some examples to give context: