Ante, please provide the model year of your coach, because heating systems varied over the years. Besides replies from owners of similar rigs, you may get links to owners manuals, etc., that can help you learn.
You can certainly use a thermometer, as many of us do, to monitor room temp., just as anywhere else. I use a large character digital clock/thermometer on a living area slideout sidewall that I can see from the galley or while watching the front TV from a sofa. It included an outside sensor that I mounted protected under the front cap; so I can read inside and outside temperatures as well as humidities on the one wall clock.
Joel