I'll be building a new instrument pod. The tablet display is about the same width as the area the actual gauges take up on my '92, but a bit taller. So there is more actual area for the gauges, but a new pod is required for the extra height. To the left and right of the tablet will be lights for turn signals, high beam, 4WD, etc. To the right of that will be another flat panel display for navigation, music, radar detector control, etc. Depending on how ambitious I get with the new pod, I may have a 3rd display in the center of the dash.
It's possible to use the current pod I think, and have a slot in the top of the pod for the bezel of the tablet. There's a lot of details and un-answered questions that I'll have to dig into and start fabricating before I know all of the answers. That'll come this winter.
Switching the display will either happen by swiping the display left and right or touch buttons. I haven't decided yet. Another thing for this winter. (I'm too addicted to kiteboarding to spend much time doing anything else April through November...)
I'm not familiar at all with any fuel modes that can be selected. They don't exist on truck motors as far as I know. Tow mode--as you mentioned--is a different shifting pattern. It has to be activated with a mechanical switch, and you must have a BCM in order to activate it. I plan on getting Tow mode active later. As far as I know there is no way to show when it is active or not without factory gauges. You could rig a mechanical switch that would cycle a light, but it wouldn't actually show Tow mode, it would show even or odd switch cycles. So if it got out of synch it would show the opposite of what you have.