B.C.
Good morning,
I know vacuums seems bulky but when i clean houses for people i just use the big vacuum, set it on the step or second step down from where im cleaning and use an attachment on the hose and vacuum each step. It really isnt too hard at all once you get a rhythm down. Stairs are always a pain but you could also use like one of those hand held vaccuum's i dont know if they have enough power never used one but its an idea.
Have a great day hope that helps