I used 705's on my KLR, really liked them and think you will be fine with the mileage. The but part, is that chip seal and sharp edge gravel is hell on tires. So it depends...Just watch the rubber.
Since your riding into twenty plus hours of daylight who needs a headlight? I would look for a wire headlight guard or that real heavy plastic stuff. A thrown rock is the problem not a burned out bulb