Holes on top of my plastic tub winter heating questions

I have a UTH one hide with half of it directly under a heater. And water on the cool side. Temperature is around 30degrees Celsius and humidity around 50 but at times drops down to 45.
Is this ok? Is it wrong to put holes on the top of the plastic tub?

Second question. Japan doesn't have central heating. We have basically an Aircon that can do heating, air con, humidifying and fan although a bit costly to keep on the whole day considering winter is coming. My question is can a UTH and a plastic tub sustain enough heat even if the room temperature becomes as cold as the outside(an extreme scenario). Or should I leave the heater or buy a cheaper heater strictly for the bp so monthly bill isn't as high as using the air con machine.

I know it's more than one question but thanks for the help in advance.

1. Humidity of 45 should not be a problem. You do not give a reason for putting holes in the top of the tub. So I cannot judge whether putting holes in the side of the tub might be more effective. The edges of the holes should be smoothed to avoid damage to the ball python's nose or skin, of course.

2. I checked out the maximum and minimum temperatures for Tokyo. https://weather-and-climate.com/aver...ne,Tokyo,Japan In my opinion, a UTH and a plastic tub cannot sustain enough heat for a ball python when the room temperature gets down near 3 degrees Celsius. Insulating the cage may help. My place has central heating, so I do not have any good ideas for you. :(

Holes on top will allow humidity out easier.