I guess what I did goes against most suggestions, but I just put all of mine in 37 quarts tubs. 3 of them were 140-150g, two of them were under 90g.
Two hides (one at warm end, one at cool end), a water bowl, a few crumpled up paper towels, and a couple of toilet paper/paper towel tubes in the tub with them.
They've all eaten very well (except one, but she had an RI when I got her). All started on live mice and switched to FT rats with no issues. All growing nicely.
For myself, I'd rather get them 1 tub and just remove items as they grow than buy multiple tubs to swap out as they grow.
There's no one way to do anything, I just figured I would post my experience and what I did.