Even using a third party app like Mixing Station Pro isn’t going to allow a mix (no pun intended) of LR and aux mix faders on the same layer. With Mixing Station Pro, the ‘sends of fader” buttons can be a part of the screen design, so you can have a layer with faders 1-5 on the screen. Normal functionality would be to control FOH, but by pressing the correct aux “send on fader” button located on the same screen would change the functionality of those faders to control the selected aux send. You could quickly press and change levels for any aux or FOH and the screen layout (faders 1-5) wouldn’t change other than to reflect the fader level of the aux or FOH send.
That is probably the suggestion I would make. Try something like the Mixing Station Pro app and create a custom layout with the needed channels and the “sends on faders” widget on one screen.