To go from bed mode to seat mode is actually only a one-handed operation (I've been doing it wrong). If you lift the front cushion up far enough, like rotated up and back towards the rear of the bus around 90 degrees or more, it will click and stay upright. Then you can just pull down on it and it will bring the backrest upward with it... amazing! I always pulled the back portion up manually while pushing in on the lower part.
I'm sure I've slept in the bus at least a hundred times in the nine or so years we've owned it. Not sure how many model years this applies to but ours is a '70 as mentioned in my sig line. Owners manual doesn't explicitly state this but is somewhat vague.