Back with a new question! (I would have just added to my first thread and edited the title to indicate a new question was being posted, but I don't see an edit option - correct me if I'm missing it?)

I'm going to be building my own enclosure and would like some opinions on which dimensions would be better for a juvenile BP. The snakes I've been looking at on Morph Market tend to fall in the 100-250g range depending on when they hatched in 2020. The two enclosure sizes I've plotted out are 30"x18" or 28"x16" (height probably 12-14"). I'm happy to go bigger (or smaller?), I'm just running into conflicting info on whether bigger is in fact too big for younger snakes. As far as hide box size, am I right to think the medium RB box is too large for the size of snake I'm looking at? In the picture I've cut out a medium box size paper, and a smaller one with dimensions of a small hide I found on Amazon since the Reptile Basics small seems too small. Which would be better to start with?