Look I know everyone is saying don’t but I think you can do it pretty easily. So I have seen masons do brick and stone facades in the middle of winter. They had concrete blankets and diesel heaters. It worked just fine. I would get two tarps and a blanket and build a little tent with tarp, blanket, tarp. Then put a little electric heater in there. Newer electric heaters are much safer than the old ones with the ones exposed resistance elements. Just think you don’t have to get it really hot. Not like it is going to catch fire until a few hundred degrees as long as the heater is not touching the tarp there is no real chance of that happening. Plus if it is just barely freezing at night then it really just needs to really work for a few hours.