3050DS rear ladder add on

Just picked up our used ( new to us!) 2016/15 3050DS-CD. It has no rear ladder and I would like to add one. I have been advised by the dealer that because of the full side slide for the bedroom, there is not enough supports to add a ladder. Dealer would have to remove back wall and add blocking, which would be very expensive. Has anyone else faced same problem and have possible solution.
Thanks