3rd row seat.

[Ronbo]

This setup isn't bad as long as it wasn't driven on the street. Little heads are still right by the rear glass. Helmets would help.

I understand the safety concerns. But it appears the rear seat passengers are further from the glass, then the front seat is from the B pillar!
My head hits the door beam on my 2-door with the seat belt properly installed. My head hits the B pillar on my 4-door just by tipping to the side a few degrees. I'm all for building the safest possible rig, but we'd probably be best served by walking.

 

[92xjunk]

I would suggest using some sort of prophylactic. 4 kids= way to much stress.