We don't use our main awning very often, but don't think I would want a rig without one.
I would never have any kind of RV without slide toppers! Its a PITA to get up there and sweep off the top of the slide before retracting it!
I would consider the ladder an essential item also. It would take a pretty tall step-ladder to be able to safely climb up on the roof so it would take up a lot of storage space. I don't think a permanent ladder would be very expensive so I would definitely have that done.
Good luck, happy trails, and God bless!