Honestly, my "welding table" was an old aluminum router table. I never did rely on the connection from the part to the table for the ground connection, I'd always clamp off directly to the part, and sometimes run a secondary cable to the other part if I was concerned about poor contact to either side of the joint, though usually my clamping mechanism was good for the ground connection.Table is zinc coated to help with rust, so the manual states. I will open the garage door next time to maximize cross ventilation!
Especially since you are working indoors, I'd consider bolting a 1/2" steel plate to the top of the table.
What I liked about my aluminum table was I was absolutely not going to stick my work to it, and any spatter easily brushed off.