Are the tubes going up to the second level round in cross section?
I've got a couple of handy shelf things in my drum kit that i clamp onto the highhat stand for drumsticks and a cymbal stand for general percussion bits and pieces. I got them in Drum Central for about £40 and mine are made by pearl, but I expect there's a few varieties. They're about a foot square with a lip round the edges.
You can see one in the left hand edge of this pic:
