The bottom would work in that manor, another option for the bottom would take a solid piece of maple that is 1" wider on all sides and make an 1/8" deep inset using your router the the size of your box so that your whole box fits down in it, that way you wouldn’t have to build a floating bottom or cut dado’s.

The top sounds like it would work as well, I’ve made a box lid using that method.

Randy - If I'm not on the computer than I'm out making sawdust.