Can you go into Yellowstone with out a guide in the winter?

So i want to go to Yellowstone in the winter on snowmobile. But i want to be able to stop whenever i want and take pictures, and go see what i want to see. Is the only way to do it through a guided tour. I want to see if i can see wolves and the other wildlife because i hear winter is the best time, but it takes patients and i cant be holding up a group all day and i dont want to feel rushed. Is they only way to do that through back packing? If i do have to do a guided tour what is the cheapest way to go. Im 18 how old do you have to be to rent the snowmobiles?