This actually can work pretty well by using Dante cards in the surface. One of the GLDs – probably monitor world – owns the stage boxes And analog gains. The FOH GLD is connected via Dante to the Monitor world GLD and mixes using Trim. The GLD has a function where you can set the gain encoder to be trim, so it’s actually pretty natural.
Everyone wants magic independent analog preamps, and a few boards much more expensive can do reverse gain compensation, but the reality is with the headroom available on today’s boards and good gain structure, there really isn’t any reason you can’t make it work with shared gain and separate digital trim.