Thermistor instead of thermostat in the bathroom

I have underfloor water-based heating with different zones throughout the house. Two bathrooms in each floor has separate heating zones from rest of the areas.

I’m thinking which approach I should choose to control the temperature there.

I’m thinking about separate Ecobee3 lite for living room and bedroom.

First I was concerned that humidity in the bathroom could cause trouble with such termostat (especially when it’s quite pricy). Later I figured I probably don’t really need one in the bathroom at all - as temperature changes will be felt in at least half an hour or so, it will be too late to control the temperature when I’m there. If it would be cold, or too hot, I’d probably just modify automation to heat it up in the morning (earlier, hotter or not so hot).

So, basically I’m thinking about ESP8266 (NodeMCU) with relays connected to actuators with ESPHome installed inside. For this to work, I still have to measure the temperature in the bathroom somehow.

I will have Aeotec Multisensor 6 in the bathroom ceiling - basically for motion detection, but it also serves humidity and temperature.
What I’m concerned about is that temperature near the ceiling is a bit different than in 150cm (5 feet or 60") height, which is recommended for thermostats.

So, I could install thermistor in 150cm height, connected to the ESP8266 (I have wires there, originally for thermostat). What now I’m strugling with is how should I make it “pretty”. Is it good enough if I’ll leave it underneath the tiles? Or should I place it inside power outlet or a switch box at about 120cm height?

Any thoughts are welcome, especially if you have separate zone for bathroom and have already solved it somehow.

You want the air temperature at human height. Putting a thermistor under the floor with the heating may read too high. Both of these work well with the ESP for air temperature.

I use these vented cases: