So my rig is entirely contained within an SKB 6U Roto-Rack, which is around 21" deep. I've been playing live with it on top of my Atomic Reactor cab, which generally works out fine, but it's only 11" deep.
A couple of times, it's rolled off the front during rehearsal (I caught it!) even though I center the weight of the rack over the cab. I think the guitar cable tugged on it slightly.
A standard guitar cab is usually more like 14" deep which must offer more stability. Do you rack guys usually just plop your rack right on top of your cab? Do you plug into the front of the rack?
This is a lot easier for bass players with racks, because their cabs are so deep.
Does anyone have a good suggestion for how to secure this thing better, short of just setting it on the floor?
Do you need access to it while playing? I'd stick it on an angled amp stand:
However, if the weight distribution is too far forward (likely) then putting on back to front would be the only option, which is as good as having it on the floor. Short of using ballast, but racks are so fucking heavy already adding an extra 8kgs of ballast seems...backbreaking.