Hi Robert, a heads up as to the web address would be great, many thanks for getting back to me on this.Bungee,
Retro-fitting bunk beds - either permanent or "roll-out" are a popular project for Eriba owners.
There's a handful of project reports describing how to add bunk beds on the Eriba site - (in German with pictures) - let me know if you want pointing to the right web-page.
OK, you don't have an Eriba and you'll can only use these as ideas, but they should point you in the right direction.
Robert