There are two supports on either side of the yoke but you make a good point. Its supporting fine now but once I add more things could get hairy

Don't let the name fool you I'm not really a master of anything

JSpahn wrote on Feb 4^th, 2008 at 5:19pm:

Yes... but they rest on another piece laid flat, that is only supported at both ends...I've done a lot of good and very bad carpentry, and I see those screws at the end "blowing out" someday when somebody leans on the panel or whatever.

  If I may suggest: add some thing smaller, maybe even 1x2,  to each of those "shelves" at a right angle so that you now have an L or T-section... much stiffer, but not much heavier.

Then glue and screw some 1x3 or something flat on the inside of the box between the ends of the shelves and under the lower one, extending vertically- down to the base would be best, because that will transfer some of the weight of your panels to the floor without stressing the joints at the ends of the shelves... but with that overhang, that wouldn't work.
I dunno; I'd mainly beef up those ends somehow, even with little cleats or small metal corner braces.