Re: 2009 T&C with stow and go, I need help with carseat placement!
The 3rd row seat is a safe and appropriate choice for the 4 year old, so I wouldn't take the risk of being rear ended into account when figuring out where to place everyone. I personally would keep the 4 year old in the 3rd row installed with LATCH and the baby behind driver. With a rear facing car seat on the captains chair, I can easily reach back to the 3rd row to help buckle my other kid (I have the same van, MY 07). It was harder for me to reach when I had each car seat on a captains chair. If your older kids prefer the comfort of the captains chairs, you could put baby in the 3rd row with 4yo and load from the hatch. I personally don't like doing that, but I'm very short and that's quite awkward for me. It works for many people.
Child Passenger Safety - Instructor
DS1 - 8 DS2 - 7 DS3 - 3
Expecting a SurroBaby 12/12/13