I have 2 ladders, 3 if you count the one on the coach, (not a TT), and many TT's do not have walkable roofs, so the ladder is just to see the roof. I just sold in the yard sale one of the 12' collapsable ladders, drope to about 20: square, Used it for many years. I wanted self standing to keep, so have the one that fold to a 4" square by 5' long. Tall and stable.
Sure, you can almost always borrow one, but at times that doesn't happen. Transporting an RV last year in AZ, awning started unfurling, and no amount of messing with it from the ground would do anything, had to get on the roof, and would have been a lot easier to work from underneath. Wished I had my ladder with me.