Trying to keep my beardie warm help ASAP

My furnace is broken and our heat isn't working and no one is available to fix it right now. The outside will start to get warmer around Monday but it's lasting till then. It's °16 c /60.8 f in the house rn and his tank is 90f/32c which is about 15 degrees less than it should be (it should be about 105 f) We don't have any money till Thursday so we have no way of buying anything to help keep him warm and turning him off for the night is giving me anxiety cause last night he dropped below 80 f. Does anyone have any idea on how to keep him warm through this? I have added a cotton shirt under him to try to help him warm and he has barely moved from under his heat light all day. (He does have good lights and they are warm enough the house is just too cold). My mother thinks we should leave his light on all night so he doesn't get too cold but I'm not sure if that is a good idea. He isn't cold right now but he isn't as warm as he should be and honest I'm anxious and need some ideas. Thanks in advance. Oh, also he is 6 yrs old so he isn't a baby.

Update the cotton teeshirt under him seems to be helping with his heat holding. I'm still not sure about the night though should i turn him off or keep him on?

As long as it doesn't o below 63 F it will be fine. Keep the heat lamp on longer than usual at night [ a couple extra hours ] and turn it on an hour or 2 earlier in the morning. If it actually goes below sixty at night, put an upside down cardboard box over him with a hole cut out out of one end and keep the lghts on all night, but not directly over the box so it doesn't get too hot but keeps him around 75.