First, I have neither done nor seen this done before. With that said, one thing you should and probably are considering is the width of the bench seat. The Chevy Astro has two full bench seats(seats three), but the other vans, i.e. Caravan and Windstars have a partial bench seat (seats two). This allows the passengers to have enough room to get to the back seat. Since this will be an issue for you, you might want to consider using these "partial" bench seats to allow for room for people to get to the back.
Never seen this done, just one more idea.
