Yep you're right. I researched more since then and asked around. I 'could' wire a subpanel off of what I have, but it wouldn't be to code. I'd have to bond neutral and ground wires at the subpanel for 115v circuits running off of it. Apparently current NEC calls for the ground and neutral wires to be isolated at the subpanel and running back to the main panel, which I can't do unless I had a neutral running back to the main pain.
I just made it easy on myself and wired one 230v receptacle off the existing wiring in the ac disconnect. I also sold my Hobart Handler 140 and bought the HH 210 MVP. I can work with the 115v plugs already in the garage for grinders, portaband, chopsaw, etc.