I agree with what others said above. An 8' plow will be a little too small only because with that long a truck, your rear wheels may be riding in windrows when you turn corners while plowing. I would go with atleast an 8'5" to 9'. Obviousley if you plan on doing commercial, the Blizzard 810 is where you will see the most benefits. As said before, I don't know if I would start off asking how to plow at the end of august and then jump right into commercial come November-December. Do what Mick said or what Jay said. Do you know anyone you can "sub" for to get some experience, it will help quite a bit. I plow all residential on my own and sub for a landscaping company when they need me, usually for clean up work. I can tell that I have my hands full with 37 residential accounts, commercial is very hard to manange on your own especailly the first year. If you sub for a year or two, it costs you less money and legwork initially and then you can decide if plowing is really something that you want to get involved in and decide weather to try it (it being commercial) on your own. If its too much, you can make a good amount of money with less liability on residential accounts.
Look around on this site, lots of great info and people willing to help with anything you need. Welcome.