A two hour mission tires you to the point you cannot properly function?
Crew of Three....even if Single Pilot....shared duties using CRM concepts unable to cope with a two hour mission?
I would look beyond the actual duration of the current mission and consider the entire Duty Period to the point they crashed and consider that as a more important concern than an actual single mission length.
Fatigue must be considered but we have to remember that is a function of several variables and each should be weighed in the evaluation of fatigue/crew rest factors.