Resize Camera to envelop a randomly generated hex grid

I'm trying to make a camera that can see the whole hex grid for our game's minimap, but our hex grid is randomly generated at start up, specifying only the width and height of the map (# of hextiles horizontally and vertically). So far my only idea is to use the 4 corners of the hex grid, but I've no idea how to make sure the camera corners have the same coordinates as the 4 map corners.