The bunk bed attaches to a piece of wood via hinges. The piece of wood is fiberglassed to the shell under the front window. I used heavy duty stainless steal door hinges for mine and 3/4" plywood for the bed. The factory bed was 1/4" plywood with
light duty steel hardware.
The only trick is cutting the sides of the plywood bed and installing hinges so it flexes with the curve of the front shell.
I am sure there is a script with details and schematics somewhere on this web site.
If you can do it yourself, do it yourself. You will only
fall deeper in love with your camper since you put your own sweat into it.
Mark