My mistake as you not wanting to see the hinges but flush hinges would work best as they have a very small knuckle! The problem you have is that they are egg cup construction so any decent concealed hinge would require you fixing in the back which may miss the guts of the edge of the door. And...
I understand the doors your talking about it's what we call 'egg cup' but they do have an edge on them so you could fit flush hinges which requires no pairing out, I will try and send a link...
Hi Dan,
Some doors like you said are hollow are what we call 'egg cup' they are cheep but do have an edge on the so you you can fit something called flush hinges and you don't have to pair the hinges out, its an easy fix for you self!
I tried to send a link but it was to many characters!