The answer depends on the pedal, your foot, your finances, and your preferences.
#1: If you are fanatical about center hits, #1. Don't remember what you are using on your Cats, but I like this one, because it is dead simple, and the pedal can adjust to left or right to compensate for Sonor's off center pedal designs.
http://www.google.com/products/catalog? ... ps-sellers#1 and/or #4: If you are fanatical about your pedal setup, then you are driven to using a riser and/or a second pedal. But even with a certain amount of flexibility in your approach, the shift of two inches is pretty large on rotating mass. It will really affect the feel, so you probably won't be able to reproduce a dead center hit with one pedal, without a riser.
#2 and #4: The luxurious solution is a pedal for every kick. That way, you don't have to rob Peter to pay Paul, and Peter's can keep his pants up in the bargain. The less lux solution is to make a mark on the beater shaft for either drum, which is a simpler version of #2.
#3 and #2: If you don't mind off-center hit (which I don't), then this. You can add a second beater if need be (most beaters will need to be shortened to use on an 18).
Cliff, you write too fast.