One downside with me and the T800 is, it is a 2 in one front / main unit system, and so i would have to put it offset for the interior camera to properly see the cabin, here by far i prefer Viofos remote interior cameras you can put anywhere along the top of the windscreen or even further away on a longer cable.
So when i sample cameras like this i remove my mirror to be able to get proper good undisrupted interior footage in, but TBH it can often be many months before i remember to screw my roof mounted mirror back in place.
ATM i have the T800 offset a little to the left and the Vantrue S1PRO Max offset to the right, leaving room for one traditional wedge camera right smack in the middle of it all.
The Vantrue have a big + in this, its lens can also be slightly angled to the sides, which nicely compensate for the offset position, today not many cameras have this option only up/down adjustment which is also fine if you have the system right smack bam in the sweet spot for a dashcam.
Of course that is me the addict talking, a regular user just having one system to work with only have to consider what might be best for the particular layout of his windscreen which can be " complicated" by sensors ASO.
Sadly after site rearrangement i have lost track of the nice PIC heavy thread of peoples installs, it was a nice thread to browse to see what might be possible with layouts somewhat similar to what you might have.