The lunar surface temperature is like -150C at night. And yeah, heat loss is radiative.. to a sink at roughly -273C. And night is 2 weeks long. Just use solar heaters and insulation? Well you have to fly that stuff there first, and also fly whatever equipment and people/robots to make the system.

There are various studies to have stuff survive lunar night without a nuclear source, and it takes on the order of 10kg of stuff to keep a 1kg payload alive. And in turn that takes 100kg of spacecraft/fuel to fly it all there. That’s not including the rocket and its fuel to get to Earth orbit first.