Join Date: Feb 2010
Location: Philadelphia area, Pa., USA
Bikes: Santana Cabrio triplet, Santana Fusion S&S tandem, Co-Motion Mocha S&S tandem, Co-Motion Pangea S&S, Co-Motion Nor'wester S&S, C'dale F2000
Generally speaking, for a stoker kit (aka Stokid Kit) you need a good bit of open real estate on the seat tube. Of the three tandems you listed, the Pacific has the best setup as far as that goes. But, as mentioned above, you might run into some problems with the top-pull front derailleur cable. You also need enough tube there so you can get the child adapter up high enough that the upper cranks don't hit the lower cranks.
One thing to be aware of with lower-end tandems is to make sure the stoker non-drive side crank has removable chainrings, as you'll need to add a second chainring back there to provide the chain interface with the child kit (i.e., you'll have two chainrings on the rear non-drive side).
At 5'2", I imagine you'll have some challenges finding a tandem that will fit you in the front and your child in the back with the stoker kit. If you are willing to spend more $$, a Co-Motion Periscope will solve most of your problems and you won't have to use an adapter kit, either. You might keep you eyes open for a used one, although it will still be in the $1500+ range.
Don't overlook a Burley Piccolo tag-along ("instant tandem") bike, too. I wouldn't touch most tag-alongs, the Burley is in a class by itself due to it's excellent design. We had one for a while and really liked it. Price is not much more than buying a child stoker kit on it's own, and even better if you find a used one in the $150-200 range.