Everything you have described so far sounds like a stressed snake.

Perhaps you could try filling the enclosure with crumpled paper to simulate a larger amount of "cover"? Then over time, start removing more and more of the paper until there is none left.

I would give substrate another try. She might not like it at first but she should get used to it after a few weeks. Perhaps she doesn't use her hides because she doesn't like the tile.

I know your husbandry is spot on but some snakes are a little more picky when it comes to security.

I don't know where you would find them but I have locks on my boaphile cage that work perfectly. maybe you could check out their website so you can see what they look like and try to find something similair.

Good luck! She does seem like a handful