I negotiated a bunk ladder from the dealer as part of the deal, when they stopped coming down on the price....
they gave me one that looks just like this, loose
Stromberg Carlson RV Bunk Ladder - Aluminum - Black - 60" Tall Stromberg Carlson Enclosed Trailer Parts LA-460B
I cut it down for better fit, and had to jurry rig the mounting clips a bit, but it turned out ok.
Sorry can't find a picture to share.
I find it a shocker that it's not factory standard.