I had 3 kids in the back of my patriot for over a year (before we got pregnant with #4, and had to go up in seating count).
Smallest forward facing kid behind the driver, largest forward facing kid behind the passenger, rear facing in the middle. Only way to go. We also went to babies r us, and they allowed us to measure the seats with a tape measure, and then took the ones we were interested in out the car, and fit them and make sure they actually fit
Congrats by the way!
I'll drum up a picture of my kids here in a moment in the back.
Here you go:
Oh, as a parent pro tip, Get seat covers, fold some towels, put them down, put the seat covers over the towels, that way if something is spilled, it goes into the seat covers/towels, and not the seats. I've had kids puke back there, and the seats still looked brand new.