Hi Scott

if I understand you right, you want to put something on top of your PSR2000 like a small 19" rack or 19" halfrack. I did this with a 19" halfrack sized KORG NX5R which is something like a small sound expander.

I use a... of what is it in English "Klettband", it is not a zipper, it is something you find on shoes like a ribbon(sorry babylon has no translation)...

but here is a picture
http://www.fiber--optics.de/Produkte/Montage/klettband.htm

There are types of this with glue on both sides. You put one on your PSR2000 (above the speaker was the best), the other below your rack. Ready... for playing bring both together... the rack is now fixed and will not slip away. After your gig you uncompress them. That's all.

Good luck

Datablues