"Otherwise we run into issues of constructs and undead creating items much, much faster than the living can."
Why is this an issue? What's the point of creating new races or templates, then saying 'oh, by the way they have to be just like humans'? Being tireless is a defining ability of both constructs and undead...the world's more believable if their abilities reflect this, instead of being contrived not to in the name of 'balance'.
If it's deemed game-breaking for constructs/undead to create magic items at 3x the normal rate, then the Dedicated Wright homonculus is horribly underpriced, since a feat and a couple of thousand gold will double any caster's magic item rate. Actually , a caster with this feat (craft construct) could get additional multiples to his magic item creation rate simply by creating multiple homunculi, one for each item he wants to work on simultaneously.
He could for example, make 3 dedicated wrights, start 4 4000gp magic items (which would normally take 16 days to make), invest 3 hour starting the 3 dedicated wrights items, then have all 4 items finished 4 days later.
So , given the existence of the Dedicated Wright, I maintain that it isn't imbalanced for an undead or construct crafter to craft at 2-3 times the rate of a human item crafter. And since it's logical that they would be able to do so (needing no sleep), I think that's the way it should be.
Ken