A hiding snake is a happy snake. Cruising around and climbing on things is a sign of STRESS which is why your snake is aggressive.
Changing environments is stressful but after a week, they should be settled in and will be happier in the long run.
Your snake can get sick if the temps are too low (which I am sure they are in something so huge). Having the top covered doesn't help.
If you are worried about spending too much money then maybe you have made a mistake. With any animal comes a responsibility to be able to provide for it. This means having extra money for food, vet bills and if needed, new equipment.
I think dividing the tank might be a good option. You could try that. I wouldn't start handling regularly until the snake is eating on a steady schedule.