Gary, when I was a kid we jigged codfish maybe 1/2 a mile off of madaket one time in early spring but that was a rare thing.
I know my dad tried bait off the beach at sankaty for cod a few times but I don't think he ever did anything and he wasn't very serious about it. The current and surf make it tough there.
As to the perch fishing, there's no bass down there (Large or small mouth) so the perch get big, so do the pickerel. I think a few of those big fish came out of long pond and more than a few large perch fell to a guy who fished in a float tube. I know there's big ones in Sesachacha too, but the only fish I ever caught in that pond were stripers that got landlocked when the pond opening closed.
There's pretty good access there on the beach side.