My power steering and ac went out and I'm curious if you can bypass the both of them and put a smaller belt in the bottom in to the fan / water pump

 

A smaller belt may be possible IF,
none of the pulleys you don't use get in the way of the belt, and it is not easy trying to drive a vehicle that has power steering and you have to fight it to steer the vehicle when the power steering is not working.

 

You can't do that for the power steering. With power steering, the gearing is such that it will be very difficult to steer especially in situations where quick reactions are needed. The old manual steering systems are geared where it is easy to steer the vehicle.