With a building consent application there is such a thing as an "alternative solution".
The Building Act tells you how to do it, the building code tells you what has to be achieved and 3604 tells you a way that the code can be achieved. An alternative solution can be achieved with a fan wired to the light fitting, the same way that you can do that in an internal toilet compartment. What you are proposing is not an occupiable room such as a bedroom or a lounge, it is similar to a toilet compartment or a store room. You don't need to tell them how many hours you will spend in there playing with your fish (you only need to justify that to her that will be obeyed).