Heart Set
I would not get your heart set on only one job. Fish and Game flying jobs do not come open all that often. I would get into flying because you love to fly and not because you have a specific job in mind. By the time you get there most likely the conditions will have changed.
If you would not be happy flying for Mesa or any other company then perhaps you should reconsider. It can take many years to build a resume that will attract fish and game and by then they could have sold the plane and hired a contractor. In any case a lot could happen to spoil your plans.
Hope for the best but plan for the worst. If you do than then aviation shall not disappoint.
Skyhigh