Can't find it right now, but I have seen pictures where someone did some mods to the little compartment in front of the shifter and stashed a 2 1/16" gauge in there. Easy to see with the door open, hidden with the door closed.
I've also seen them installed in the glove compartment so you can read them with the glove compartment door open, but that's not very convenient.
There's also the Aeroforce 2 1/16" gauge pod that takes the place of the side window defroster vent on the driver's side, easy and clean solution.
What I would be tempted to do is buy a spare center speaker cover for the middle of the dash above the screen and mod it and install a couple of gauge pods there... If you retain some of the mesh you shouldn't affect the stereo output that much.
As far as where to put the sensor in the downpipes... it's pretty limited access to get a wideband installed pre-cat if you're running catted downpipes, especially if you want to keep the sensor pointed above horizontal so it doesn't collect moisture and potentially damage the ceramic during warmup. If you're running catless downpipes, you have a lot more easily accessible places to install it.