There is an Israeli company called BUL that makes a plastic-frame 1911 that holds a bunch of rounds. Kimber used to import them, and I think Charles Daley does now. I've heard they are nice, but magazines are a problem. They are apparently nearly impossible to find.
That may have changed with the new import deal with CD. I hope so, anyway. I looked into getting one a while back but held off because of the mag situation.