There are plenty of smart home gadgets to automatically set a control cycle for temperature control. I had a quick look over the internet in a big store in the US and was very fast in finding: wifi sensor temperature, wifi smart plug and a small room heater for affordable prices.
Go like this:
1. Google for apps that integrate the hardware you desire;
2. Check if you can setup scenarios in it (e.g. Turn plug 1 on if temp. < 68 °F);
3. Get the stuff and place the heater output a few inches away from the air entrance of you tent;
4.Watch it
This is though a very simple solution and the reliability of the control system depends, of course, of the hardware/software you choose. For example, see the beginning of my journal, I'm using tuya Plattform for that. As it's not that reliable, I decided to "outsource" irrigation control because I kategorized this kind of loop as critical (I've got critical / major / minor loops to control) It's just about risk mitigation, bro - if something goes wrong, what can happen? Cheers