1. do an aftermarket head unit (AHU) and use the smaller blue non-touch screen in the upper portion to purely show climate control
2. do an AHU but use a climate control capable AHU and the maestro RR idatalink connector? Then probably just use the upper portion for a small tablet connected to OBDII
Correct.
You can choose one of them, or you can combine both, and use both blue screen and idatalink for climate control output, then you will be able to see the climate in two places.
iDatalink-powered climate control does not show outside temperature, when you turn on the AC, but it shows it when you turn off the AC, and blue screen will show both. I plan to request idatalink folks to fix this soon, but not asked them yet.
use the upper portion for a small tablet connected to OBDII
iDatalink also can connect to OBDII and show different info like some gauges and TPMS (on compatible vehicles, on 2016 Ultimate TPMS works well, can't say for 2013).