I decided to go with a GP Logistics SLDD7 7' Compact Folding Ladder:
https://www.amazon.com/gp/product/B009IJUL4O/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I like that it takes little space in a pass thru compartment and isn't as heavy as the "little giant" type ladders. I have a Werner version of the Little Giant to the S&B house, but found that it would take up more room, is heavier and more awkward to stow and remove from MH storage compartment. I do have a OEM ladder on the back of our Newmar, so the GP folding ladder isn't my only option for getting on the roof of the motorhome.