Hi Dan, I have been thinking about your project, specifically the use of expanded wire mesh as a floor. I am thinking the edges may have to be overlapped with lightweight angle iron or flat stock to cover the sharp/jagged edge and to secure the mesh in place. Many small tack welds are prone to breaking, I know in our shop we are constantly repairing gates and mesh floors, albeit they are getting abused with mowing equipment.
Just my .02 cents
Frank