Here is the progression of set ups I've had my Candoia bibroni bibroni in. Remember I am in their native country, so there is no heating or misting used - just open to the natural conditions (make it a LOT easier). I have added an under-belly heating pad on very cold winter nights (when it drops to 65oF lol

), and they like to cuddle it.
I do not keep mine in plastic tubs - I prefer aquarium style tanks, and (against most of what seems to be done by most keepers) I keep multiple snakes together, as do most of the other people I know here who keep them. Part of the reason I do this is that I find these snakes very active (particularly in the evening) - they like to roam their tank and climb branches at night, and are often in different hides every morning. Also they really do seem sociable and genuinely prefer to sleep in a bundle with each other - I'll post again about that.
So far, no problems, but I take many precautions to avoid the issues seen as a negative of housing multiple snakes in one tank:
I DO NOT feed the snakes in their tank - they are removed to a plastic feeding tub every time, and fed alone, to remove the risk of them biting the same prey animal.
I DO NOT regularly add or remove snakes to my collection - I started with 2, added a third after a year, then left them alone for 2 years. I had a breeding loan female for a month this year, and then last month I added a collection of 5 more (see later). Each time I have added snakes they have been ones I have personally been in contact with, from owners I know well, so they have effectively been in quarantine for many months or years.
I DO offer multiple hides of a variety of sizes so that they can all find whatever shelter suits them.
I have also had to be somewhat flexible and experimental, as I am not in a place with herpetology supplies:
Tank 1 was a cracked plastic fish aquarium and it was great for 2 and then 3 neonates until they were about 60cm (2 feet) long, then it got crowded.
Tank 2 is actually a collapsible plastic /canvas portable dog kennel with zip-up mesh sides. It was GREAT for 3 males who'd never get larger than about 1m 30cm (4 feet). They'd still be in it if I hadn't got the larger females.
Tank 3 is a custom made wood/ plexiglass and mosquito netting cage made by the father of a young keeper who had 2 large and 3 small snakes in it. I have just inherited both tank and snakes, so it is currently housing 2 large and and 6 small snakes. It is VERY big - initially seemed ridiculously so, but in the evenings they do roam the whole thing, and I like to see them active. In this tank there are three climbing branches, two water bowls, and 6 hides of varying sizes.
All of them come out onto the branches in the evening. Some of them like to soak in the larger water bowl after feeding, others I never see in the water. During the day the smaller ones like to be on the ground in hides, the larger females sit up in the branches, like tree boas.
Anyway, obviously there are many ways to do this - just thought I'd share what is working for me.