Unfortunately I never got a satisfactory response to this.
What I have realised though is that the ‘mobile’ version is invoked when a mobile device is detected (as opposed to a starting screen resolution being a certain size).
Over time I have also become more comfortable / successful with using Bubbles responsive rules, particularly this gang:
As a result it is very rarely that I’ve needed to create a separate mobile page.
Good luck and shout if there are any specific examples you need a hand with.