Have you considered spray basting outside? It's pretty inexpensive to purchase a couple of sawhorses and a sheet of plywood to lay on top of them. You need a storage space for them when not in use (garage!), but they store fairly flat and don't take up a lot of room.
If you have a garage, some people use an inside garage wall (taping to the surface) for spray basting. Another option is to purchase a couple of 4x8 foam boards from a home supply place, create duct tape as a hinge for them, and prop them against the outside of a house as a smooth surface to spray baste.
One nice thing about spray basting outside is you don't have to worry about overspray!