[Navwizard]

If all you are trying to do is add Carplay and Android Auto, the cheapest way by far is to add one of those interface boxes.
In my F56 I added Carplay to the OEM interface, but for my R60 I added the one below and it works great. $259.

You are right space is tight, but the box isn't very big.

You just hold the menu button for 3 seconds to switch between oem and CarPlay/Android Auto, so lose no oem functionality. Wireless as well.
You don't need a touchscreen to run it, it runs fine from the joystick. In fact in my F56 I have a touchscreen, but still run it with the controller.

Wireless Apple CarPlay Android Auto MMI interface adapter Prime Retrofit For BMW CIC NBT EVO System Series 1 2 3 4 5 7 X1 X3 X4 X5 X6 X7 Mini I3 Z4

The other option is you can replace the head unit in your car with an NBT EVO headunit. It's not super hard, but is more expensive of course. Then you can add Carplay to that. (but not Android Auto).

There are options.