Beds 2003 Duetto

Hi all, 
We have a 2003 Duetto, we normally use one of the extra cushions on to the back of the drivers chair and the support on the end of the sofa. And turn around the passenger seat and use that for the end of the other side of the bed.
This works pretty well, but does leave a few gaps at the cab end.
According to the manual the proper way to have the double bed set up, is to use all three extra cushions, the wide one in the middle and the shorter ones each side. I have tried this, but the cushion on the passenger side sits on the support behind the chair and is much higher than the other side, also there does not seem to be a proper support on the other end.
I wondered if anyone else had tried this.
Cheers Rob