For what it’s worth, I put plastic washers between the SKB A/V shelf and the Qu’s rack-ears, so as not to scratch it. I had to double up on the washers for the overhanging 1U space above the mixer, but it’s perfectly leveled. I was going to bolt a mic flange-mount to the shelf, to attach a gooseneck for talkback, but then the lid won’t close over the extended height of the flange-mount, so I’ll have to get some sort of quick-release clamping mount instead.
Operation of this shelf should get in the way of both a gooseneck podium mic and the Allen & Heath proprietary LED light, directly connected to the back of the console, unfortunately.