Hi Colin, I'm fairly sure everything's as far on and in as it will go, gave it all a good tap. Even so, the axle doesn't fit through the carrier as far as the old one. I share your sentiment about the nut position being odd, I haven't tried without the seal, I will do on my next attack, but I doubt it will make a difference as it wasn't being compressed in the first place as the hub wouldn't get close enough. I didn't replace the bearings as they're timken and in good condition.
Just thinking 'out loud' as it were, even if I got the axle to sit further in the carrier and solve the hub spacing problem, that would still leave the nut too far in. It seems the whole assembly needs to sit further in but the hub needs to sit further out on the stub. I am somewhat baffled and would love to be convinced I'm missing something obvious.