Hey Grasshopper,
this will be easy. If you are going to wrap or apply finished end panels and faceframe on all side of the island I would construct the interior boxes with pre finish maple nova ply product. ( then no finishing is needed for the interior of the casework ) with only the interior of the casework being seen before applying finished end panels you can nail or screw all interior boxes together. Pre finished maple edge band can be used on all exposed edges where doors or drawer are located if any ( shouldn't need that if you are building with face-frame ). Apply the finished end panels from the inside of the casework with screws, or headless pins with glue ( you will have to sand the exterior side of the pre finished materials for glue to work best or use Rue Glue ) ( and don't forget to include gaps to simulate door gaps between end panels )
Also make sure your end panels will have the correct dimensions to have constant stile widths all the way around the casework..
Make a pre-finished box and wrap with finish panels.. This will look great.
You have the best of both world here. Using pre finish materials for the interior and paint grade exterior can clean up and look great