Dont waste your time, thats all I have to say. I've done this....look for an old thread user name beyonder ( forgot the pswd for my old account ). I used 1in square tubing, this worked good for my kids ( i only had 2 at the time ) to face forward, HOWEVER my oldest at the time was only 2 going on 3. Her legs were squished and she was not happy... I did this in a 90 ext cab ranger, I was warned about room or lack there of, but I did it anyways because i was driving from fort nelson to fort saint john and didn't like the idea of an accident in the winter with the kids sitting sideways.
The ONLY way I see this happening for you is with modifying your cab, you could literally sit the seats on the floor, but add a pan to the back of the cab to recess the seats 3 - 4 inches out. Even still with this, it may last you until your kids hit 4 or 5 yrs old...
A dodge dakota cab is also 6 or 7 inches longer than the ranger cab ( 95 model I'm refering to ).
Now I have 5 kids, and an explorer...lol, 3rd row seating is the best...
just speaking from my experience though...