I use that exact panel in my outside box . I don't have it mounted, just up on bricks out of reach. I have a similar one that is mounted that I prefer.
my russians absolutely hate my arcadia light. I even spent $260 on solar meter to make sure it wasn't to low. I've put it high/ low still doesn't matter. they won't come out of hides if it's on.
I never feed mine celery or green onions. If going to store get escarole and endive, raddichio, yellow squash, romaine. weeds and succulents are easy to grow as well as hibiscus