From forum searching I have found two useful pieces of information:

Urine can be stored in a refrigerator for up to a week.
and
After 8 hours of room temp, it begins to breakdown, possibly yielding inconclusive results.

These two pieces of info separately do not tell me how the integrity of the urine could be affected if it was exposed to room temp for an hour or so, then reheated in the morning using hand warmers, not the microwave.

So very sorry to burden you all with my question. It's only my livelihood afterall, right?

Looking through forum posts I did not find any answers that would specifically and completely pertain to my option A.