Just from the one picture of your enclosure I don't think it should be used outside. The lights will probably not appreciate the rain. Also it would need to drain and I'm not sure it has proper places to avoid the heat like a well planted outdoor enclosure would.
Being outside whenever possible is the absolute best way to raise a healthy tortoise. What concerns or limitations do you have with setting up an outside enclosure? Maybe we can help work through those.
The very best thing you could do is set him up in a proper outside enclosure. If you're not comfortable leaving him outside over night you could always bring him at night. You have a perfect climate for your tortoise and outside is where he should be. Even if your yard is fenced it's not as safe...
https://www.hermannihaven.com/comparing-hermann-s-tortoise-subspe
Chris also has a couple video's where he shows how to tell the difference if this link doesn't help.
https://toadranchcages.com/collections/open-range-open-top-reptile-habitats-toad-ranch-cages/products/6x3x16-open-top-tortoise-table-luxury-reptile-enclosure
I believe this is the enclosure they're referring to.
Box Turtles, Russians and Hermans could all be kept outside year round. Also remember that brumation is not a requirement. If you don't feel comfortable your tortoise can just live inside during the winter and outside when weather permits. With proper planning you could brumate your animals...
If you decide on a Russian I would bet you could find one needing rehomed somewhere near you. Because they are common in pet stores they frequently end up needing new homes.
Also if it is for an adult or a juvenile makes a difference on if you need a closed chamber or if open top will work. To build a closed chamber correctly sometimes the cost grows to the point that buying something already made becomes cheaper. Just an FYI and good luck going forward.