VCC powerplane layout
Don't worry about trying to make the power plane fit your ground plane.  That is: don't try to fashion the moat / island combination that you are talking about.

Your CAD package will allow clearance in the power plane when you place your vias.  You can do a complete stitch of ground-plane vias all around the perimeter of the board and the Vdd plane will have clearance holes in the power plane from those vias.  You specify how much clearance you provide in the design rules for your board.