I'm trying to figure out how to attach the side frames for the drawers. If the 3 drawers were all the same height, I would just put a lower rail from leg to leg, but since I want 2 side drawers and just a pencil drawer in the middle, I'm not sure how to attach the drawers. I wanted to use bearing glides for the side drawers and just a slot and rail (or whatever it's called where there's a groove in the drawer and a piece on the drawer frame for it to slide on) for the middle drawer.
I originally was thinking of hanging the sides off of a top stretcher mounted on the inside of the side for the side drawers. It could even hang down a bit since the drawers won't need to come up to a kicker. I'm concerned that if this isn't stable it will start racking and I'll have all sorts of problems with all of the drawers, but particularly with the center drawer.
Any suggestions?

-Ken