I've an 8" Garmin Overlander, and I'm not sure I see the benefit of a Tread over the Overlander, when the UI and maps are all the same. Yes, the Tread does have Inreach built in, so maybe that's the benefit? Do I luck out with the Overlander? No, I can go buy an Inreach and pair it up to the Overlander unit, but that is now two devices, both with their own power requirements.
When I went looking for an external nav, I ummed over whether to get an 8" or 10" unit. My primary concern about a 10" is where to put the darn thing as that's a lot of screen. Today I may have solved that problem (unfortunately).
Over the weekend I bought a Ram 1" Ball Mount, and yesterday I shaped the mount to attach to the centre console, to hold a very sturdy Fanaue mobile phone cradle. My only criticism of this position is that it's close to the steering wheel, and when I go to do a turn, my hand brushes up against it.
This morning, I realised that if I move the ball mount over to the passenger side of the centre console, I could mount my mobile phone there, or I could mount the Garmin there. So that's what I've just done. The GPS protrudes into the passenger side a bit, but I mostly travel long distances by myself, and if I do have a passenger, they can swing it around, and interact with the maps themselves. When I'm at home, and Grenny is mall crawling, I just remove the whole contraption bar the ball mount itself. If I don't want the GPS then I can attach the phone cradle to the same ball mount, and my phone is then out of the way.
With the GPS in position, I have a wireless mount suction-cupped to the window which my iPhone hasn't fallen from, yet, and it's out of the way of my forward vision, but still interactable.