First and foremost thanks for the valuable information.
I've fished the 'tip' often from boats and wished I could flyfish the deep edges from shore every time. I've seen squid and other bait explode within easy reach of the beach in those dangerous currents, and dreamed of working a big fly slow and deep in the most extreme shore access place I've seen. I know big cows cruise that edge and their wanderings bring them to the sharply cut sand bank.
I also kinda knew that (a) the flats opportunities are not comparable to northern areas and (b) the currents are very dangerous where the atlantic and nantucket sound collide. Those who are fishing both days planned on doing the traditional flats up north on Sunday.
If we (as a group) decide to do South Island, we'll have to stay up around Powder Hole and venture to fish the tip only in the soft inside eddies where fish may pull over from the fast lane.
A hazard to watch out for would be liquid sand, meaning that the current is so strong that the sand is actually suspended. Deep wading (past the shins) would be out of the question at the tip. Might be a good thing anyway in case Free Willy decides to show.
It's not easy to give up the dream of fishing as few have before, but perhaps the clave crew should consider North Monomoy / South BEACH for Saturday instead of the South Island adventure...