I have a folding 3 step aluminum ladder with tubing at the top going from one side to the other in an arch. They can be found at Lowes or Home Depot. I have the exact setup as yours in a 1998 Yellowstone. My wife sleeps on the dinette (as she is unable to get up into the bunk) and I climb the ladder to get into the bunk. I use the ladder folded and lean the top on the bunk. The ladder is stored behind the couch or could also be stored on the bunk. Also, the ladder is used outside when I need to reach anything or wash the windows.