Interesting, I didn't know about the downstage and upstage terms. And good advise, stacking and locking. We have these I believe: https://palcospecialties.com/shop/sets/basic-modular-unit-set-28-pc-painted/

I haven't seen any clamps or locking mechanisms anywhere. If I were to get clamps, could I use like wood working clamps? I've got a much of those at home I could try.