I have the same c serpents v18 rack. I also bought some v15 tubs to exchange out as needed. V15 tubs are thinner and you can fit 3 v15's in the space it takes to fit 2 v18's. I use v15's for hatchlings up to about 250g then move them to v18's when it starts to look cramped since they're only 3.5" wide at the bottom. The V18's are a great shape. I currently only have a 375g girl in there, but she still has a ton of space left.

I use 3" water bowls that fit both sizes so that leaves a lot more room. I've still managed perfect sheds with the smaller water source.

I love vision tubs and that they're made specifically for reptile racks with a handle only on one side.