Are you excluding those with tropical ponds like TLkmDN, and public displays like the Berlin aquarium which I regularly post pics of in threads like this? A 3' silver in a pond or public aquarium isn't an unusual sight IMO, and I can't help but feel it reflects badly on us as fishkeepers if our specimens in tanks don't get close to that size.
I'd be a bit concerned about the lack of depth when your silvers get big, but I guess you can try it and see.