Can I assume that you have looked at the Partner Steel square hard anodized aluminum ovens?
You can also look into the Bayou Classic fish pans. These are 18" x 12ish" cast iron "skillets" without handles which replaced the Lodge Fish Pans which are no longer made. I have two. Heavy as hell. Each perfectly covers half of a 4 burner 18" PS stove. The PS Dutch ovens are nice for nesting and storage but I'm with okieboater vs. the GSI round ones.
Also, since the fish pans are so heavy, I'll called Partner Steel and they had two left-over "lasgana" pans made as a special order for someone who never got them. They are the same size and shape as their griddles, but with 3" slightly sloping sides. Perfect for much lighter all-purpose pans. Not sure if they'll make any more though. But you can ask.