There are no true anchorage around the south side of Virgin Gorda as they aren't really protected.
The furthest south would be Spanish Town, where you can either pick up a mooring
ball or anchor
Next would be Savannah Bay, which is beautiful and empty but you need to thread in between two reefs
and I head
that a sailboat was sunk there when a squall line came through at night. I've always wanted to spend a night there but as I'd like a spotter while going in through the reef I've never gone. How much does your boat draw?
If the weather
were truly settled one might be able to anchor
(in sand, of course) around Coral
Gardens to the south side of Great Dog island.
That sums it up, the next closest anchorages are going to be Trellis/Marina Cay and the North Sound.