I had a similar problem, but I was lucky enough to be able to make more invasive changes. https://www.secretbatcave.co.uk/house/raspberry-pi-powered-thermostat

I had a similar problem, but I was lucky enough to be able to make more invasive changes. https://www.secretbatcave.co.uk/house/raspberry-pi-powered-thermostat/ https://www.secretbatcave.co.uk/house/raspberry-pi-powered-t... However its all reversible