There are limits to what a snow plow can handle. If you can't get the snow far off the road and into the ditch from the snow plow then the banks do start to pile up. You can get the banks high enough that you can't cast snow over them and then you've got a problem. Having said that there's no two ways about it; There is nothing faster for snow removal over a distance (like roads or long driveways) than a plow.
I don't know what your budget is but I would offer this advice. A snowblower alone is not very efficient for clearing a 3 mile road, while a plow alone can get overwhelmed and get to a point that it isn't effective without a snowblower or loader to remove snow banks. So the answer in my opinion is both. You could either use a plow truck AND a tractor equipped with a large snowblower or get a big Ag tractor with a front mounted snow plow AND a rear mounted big blower. My personal choice in a situation described by the OP would be something like a 150 horsepower or bigger tractor with a front snow plow blade and a big Pronovost, Schulte or Normand snowblower. You can plow quickly and efficiently with the storm and at least make the road clear in a short period of time with the snow blade. Then once the storm is over go back and cast the snow banks left behind from the plow far off the road with the snowblower. I think if budget would allow the absolute best solution would be a tractor with blade and blower as I described above with another slightly smaller tractor with a Normand pull behind snowblower. You can actually cast snow far and at a decent speed with one of those pull behind blowers.
In my opinion the ONLY option is to maintain the road for vehicle traffic throughout the season if guests are to occupy the business throughout snow season. As has been said previously things like medical emergencies, fire,etc will require that emergency vehicles can access the facility. Unfortunately maintaining the road throughout the winter is the cost of doing business.
