Tips for outdoor enclosure for Hermanni

[Albie]

We have an outdoor enclosure with wood sides, about 2 m x 4 m for our adult male Hermanni (he’s about 8” long). We live in Sweden, so he’s outside mid-April thru September usually, and we bring him inside if it gets too cool or wet. No predators or other pets, so no cover to the pen. It gets sun much of the day, but there is always a section in the shade from the sides. We’ve mostly had a few large rocks and long grass, and a plastic hide for him, and some dandelions growing in the pen, and now that I’ve been reading on here, we’re switching it up. Looking for advice. My thinking is the following:

• We’ve bought a large terra cotta pot we’ll put on it’s side as a new hide (with dirt inside to level it out)
• I like the idea of some blue slate for him to bask on
• I’m considering a small greenhouse in the pen as an additional enclosure for him, but don’t know if we need this?
• A large dish (from under a pot) to be a small pool for him (right now we have a small water bowl, but he can’t fit in it)
• Planting some flowers that are also edible for him
• Leaving the large stones for climbing
• Probably leave one of the two plastic hides (two halves of a rabbit cage, turned upside down, I think), since he’s used to these and uses them

One of my main questions is what the substrate should be? I’m thinking to leave about half the pen with the long grass currently growing (he likes to hide under it), and not sure if the rest should be dirt (with slate on some of it), or if we should put something else in?

Thanks for any tips on my questions - or on ideas I’m not thinking of. I’ve loved going thru other people’s posts and have saved some photos to refer to when I’m out shopping for things!