Getting a ball in Great Harbor is tough. If you can win the BB lottery do that and then spend the day at Sandy Spit/Foxy's Taboo/Bubbly knowing you have a spot to come back to. Then dinghy over to White Bay.
If you can't get a ball in GH, try LH and then land taxi to GH.
Bottom line; nail down your ball BEFORE going to Sandy Spit so you are not scrambling when done. Or, I guess you can anchor by Foxy's II but it seems exposed to me (NB I was there in June with more Southerly winds)