We recently purchased a quad bunk TT and like the layout. It came without any ladders to get up and down from the upper bunks. None are built in either. I know the upper bunk has a 250 lb weight limi...
I once needed a ladder for a camper bunk bed. Got on the highway, that would bring me to the next town, where the lumber yard was, and there, on the side of the road, is a bunk bed ladder. Perhaps it fell out of a pickup that was moving somebody? Stopped, picked it up and returned home. It fit perfectly. Project done.