We had three kids and a midsize car, 3 carseats in a row. I would NEVER get an SUV unless I needed to seat a 4th child, and when our 4th arrived, we got a van. (The SUV's were pretty cramped, more money, and gas guzzlers).
We always put carseats next to one another to make use of the middle seat, as it's the safest spot. Even in the van, we do this.
If you put a Diono carseat in for the 2-year-old (rear-facing since he's so young; this seat rear-faced our kid until 4.5, so it's plenty tall, trust me), and an infant seat in for the baby, that will likely work. You'd have to try. Buy Buy Baby has the seats to test out.
Infant seat in the middle might be too hard to access and click into the base. And ideally, once your oldest is forward-facing, you'd want him to have the greatest protection (since once the seat is no longer rear-facing, some protection is lost), so middle would be ideal. The rear-facing seats offer so much already, that outboard would be ideal there. But again, you need to find a set up that works for you. Good luck!