Fantastic airplanes, alright. I haven't seen any out West but I know of a guy who has or had a Turbine Thrush and also a fellow who has a Dromader.
I think you would probably start out on an Ag Truck or Pawnee and then work your way up. The Ag Truck is a good airplane and when we were spraying, we could get about 160 gallons of spray in it. That would cover 160 acres which is about the smallest field we would generally spray. The max might be over 600 acres.
Spraying in the Canadian West usually starts in early June for weeds and lasts maybe 3 weeks maximum as you generally can't spray when the crops develop past a certain point. The rest of the season to September is for insects and some years are better (for aerial applicators, that is) than others. There used to be some dessicating (chemical drying) in August or early September but I'm not sure if this is done much any more. I'm afraid I don't know anyone in the business now so I can't offer much help. Anyway, I wish you the best of luck, Chippik, and hope it works out for you.