I'm not offended by the questions at all, and I hope that I won't sound defensive. I'll go through my thinking and hope that it will be clear.
When I started planning for a snake, I wanted to be sure that I wouldn't buy something that was fine now and then learn in a couple of years that I wouldn't have room for him/her. I wanted a snake that would someday have some size, but I didn't want anything that would become too big for one person to handle. The ball python seemed to fit that description. The 55-gallon, long aquarium seemed to be an appropriate enclosure for the snake's entire life. I decided to get the aquarium now and give it a place in the house so that I wouldn't have a hard time rearranging to fit a big aquarium later.
I'd heard some people say that a small snake in a large enclosure would feel stressed, but I'd heard others say that this assertion was not an absolute fact. My impression of the arguments on both sides was that if I provided enough hides and the appropriate hides, a little snake would be okay in a big aquarium.
I considered buying the big aquarium but then buying a 10 gallon model and putting the 10 gallon inside the 55 gallon. That arrangement would look funny but would probably be an effective solution to the problem of ensuring that I'd always have room for the snake. I certainly wasn't doing this to save money. As you pointed out, the cost of a small aquarium is less than what I'll spend on substrate for the big one while I'm waiting for her to grow.
I'm also trying to add fake plants and anything else that might make this aquarium seem smaller. Someone else suggested that enough "things" inside the aquarium would make it much smaller from "a snake's-eye view." I'm trying to implement that suggestion and am always on the lookout for things that would accomplish that goal.
What are the signs of stress that would tell me that I need a smaller place for her? She eats regularly and took her first f/t mouse fuzzy last weekend. She's more of a slow, polite eater than an aggressive eater, but she doesn't pass up a meal. She had a bad shed yesterday, and I know that I'm going to have to increase the humidity. Otherwise, I don't know what signs would tell me that she isn't happy in the big tank.
Thanks,
Bill
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It's not how many snakes you have. It's how happy and healthy you can keep them.