Why not use real furniture? If you make something special purpose and one of a kind, it will be expensive, and that will violate the "inexpensive" requirement.
We use real couches, cheap ones that are light. . It is tables and bed that are the problem. I want to make something we can snap together that is light. But strong so it lasts. People don't use the furniture so maybe strong may have been the wrong word but durable would be better. We want to create something that with the exception of couches one person could move. Also something that is easily assembled and disassembled so it can be easily transported and stored.
"Staging" has a particular meaning for the military and for Fire and EMS. Your post seems to be asking about somehting else. Can you give some examples, maybe UPLOAD a couple of pictures, and post some links?