Well, for snow riding, I would not want pedal actuated motors on the bike. Id have to have very fine throttle control. One throttle can control both wheels, but I might even want a throttle in each hand for two motors. Or maybe a push button on the left hand that simply allows the right throttle to actuate both motors, or just one, if you push on the button. Push the button, both motors run.
One thing to consider, if you put a motor on the front wheel, then pedaling the back wheel makes it two wheel drive.
Living in the desert, I had little experience with snow riding. But when it did snow, a regular rear wheel drive bike worked best for me. Why? Because what you need that front wheel to do, is maintain traction and steer. Once it locks up because of brakes, OR loses traction under power and spins out, you lose your steering. Living in the north, you must know what this means. You go in a straight line till you hit, whatever is out there. Or on a bike, simply lay it down. On a car, you might spin the front tires and be ok, because you won't lay down a car. On a bike, whamo.
I did do lots of front wheel motor riding, at power levels high enough to do power slides in dirt or asphalt. Controlling that on the front wheel was incredibly difficult compared to a rear wheel loss of traction. On a slick winter road, I'd call it impossible.
I'm not saying you cant do a two wheel, or front wheel bike. But when its like that, you will need real ice tires, with studs. Thats for ice. But if you ride in 6 inches of new snow on top of packed snow, you want the fat tire. One thing about a fat tire is you run 5 psi in them, and you get great traction. Possibly enough for ice. But the traction I mean is in anything soft and deep, like snow or sand. You stick your truck in the sand in the desert, you let some air out of your tires to get enough traction to get going again. Works on snow too, to get you going again.
Me, I'd go with a fat tire bike, and rear wheel motor. Id walk if the roads were so slick you cant ride the fat bike.
3 inch tires are a good compromise, but you might find it spendy. 3 inch tire won't fit most regular mtb's, but a good fat bike is spendy too. If its for plowed roads, regular mtb, and a 2 inch tire with studs might actually work best. You might even take two motors, and put them on two bikes. Ride that cheap as hell mtb with the studs on it only when you need to. Ride the fat bike when its 6 inches of new snow.