I would guess that if you are the one driving the truck, then a clutch might not be too bad (except for the knees and the thigh muscle that ends up being the size of your chest). If you "own" it, and drive it, you'll probably not abuse the clutch. I had a standard the first 9 years of plowing, and didn't burn a clutch out once.
However, if you're going to put an employee in that standard tranny truck - plan on a clutch a year. That had been our experience, and now we only purchase automatics for employees who plow.
Additionally, let's face it. Going in reverse is a large part of the plowing operation of any vehicle (other than road plowing). So, I am of the opinion that you cannot back up anywhere near as fast with a standard as you can with an automatic - however, some guys will argue with you on that point.