Tim, This is our plan in June as well.
We took a ball in Great Harbour last May. I think it was the WillieT that was the big draw for a while. Still plenty balls available when we arrived around 4pm.
How that WT is back at the Bight, I would think GH on Peter will not be as crowded.
Plenty of mooring balls and room to anchor along the east side of harbour as well.
Let us know how it turns out, moorings and Oceans 7.