If they force you to take it out knowing that you won't be able to deliver it inside your contracted hours and are aware that you do not wish to work over your contracted hours and have no contingency plan avialable if you bring it back...that could be considered a
deliberate failure(Wilful Delay) on the part of management in much the same way that hiding it in a cupboard is.
The decision to deliberately fail mail is way above a line managers pay grade.
Some line managers are unaware of this and tend to change their tune when faced with the reality.
Keep it simple with management...only give them two choices.
Choice 1. You take full responsibility for the delivery in which case you make the decision how much you can deliver in your contracted hours.
Choice 2. Management make the decision how much you can deliver in your contracted hours in which case you reserve the right to bring back their mistake....and make it clear if they get it wrong it is their mistake.
Offer nothing else.