I actually built a shallow closet and installed a stock door to hide/access ours. It is a flush door painted same as the walls. The photos posted don't show it but the blueprint does. Hope this helps.

Best check with your local inspectors.. the NEC doesn't like ANYTHING over or near a breaker panel, how picky inspectors are about this in residential does tend to vary. The folks on the Electric forum would be able to give you better advice on this.