Asking your employer for their consent, in writing, to position of day of operations prior to an arduous tour of duty may not elicit a favourable response.
Apparently this is the process for the Air NZ boys and girls who commute. Apparently he current mood is to approve commuting although the company have flip flopped on thier view of this over time.
I think part of the reluctance to allow it was a fear of the regulator pushing for greater recognition of commute times which never really eventuated, and instead the reality that a commuter flying in from the regions would have a shorter journey to work than someone driving through rush hour traffic cause the company to relent?
Either way, it is ultimately the pilots responsibility to arrive fit for duty, and you can be sure the company will do thier best to hang you out if there is ever to be a perceived liability on thier part.