I just responded to your PM and will simply add what I said here to keep things together.

So we can get you squared away using either the glass tank or the tub.

GLASS TANK
1. Create a cardboard cutout for the top and cover it with foil. This will help train heat and humidity by simply laying it on top.
2. Using a heavy paper(art paper, construction paper) cover the sides and back. This will help retain heat.
3. Add a lamp or che to boost the temps. (You will need to have a hole in the cardboard cutout.) You will at least need a dimmer to get it dialed in.
4. Add moss to the hides. This can be made damp during a shed and it boost the humidity where the snake is most of the time.... Their hides. This will not raise the humidity outside the hides but that will not matter. I've used this trick for years with great success. If the rest of the humidity in the tank is between 40-50% I'm happy.


TUB
1. You can add a bulb or che overhead but you will need to hang it somehow so you don't melt the tub lid. I've used ZooMed lamp stands in the past doing this.
2. The same as above for adding a bulb or che.

You can get a red bulb or che if you don't want two overhead heat sources.

A che is a ceramic heat emitter. I recommend the wire framed fixture if you go with one. They last must longer than bulbs if used with a proper fixture. They get blazing hot so a dimmer will be a must.