Rear rack is the only way to go, I keep a motorcycle cargo net on it and can haul almost anything.

I have Schwalbe Marathon + on one bike and the tires are bullet proof although the ride is not the smoothest.
The other MTB has Serfas Drifters 2" x 26" and the ride is so comfy and it floats over everything, no flats on either tire after several hundred miles.
The best thing is to get rid of the knobby tires and getting the weight off your back is the next best thing.