Ken, in that size space, you might be better off with a finishing "area" instead of a finishing room.

For brush on or rag on finishes, the only reason (I can think of) that you would really need a room would be to close off the area so you could continue to make sawdust. Do you need to do this?

If you didn't have a wall, the space would still be more functional for converting to an assembly area, staging area, photography area, etc.

Another wall would give you more space for hanging items (jigs, tools, templates, clamps, etc.) and getting items off the floor if you have that need.