I don't know of a specific, off-the-shelf case, but I went ahead and got the Khomo Dual Super Slim, cut the cover off and replaced it with my smart cover. A good post that shows it is this one: https://forums.macrumors.com/posts/20316583/
It's a super simple mod, and you can see the other comments in that thread as well.
I've had it for a few months, and it's been working well for me.
I am not sure if this is the type of case that you like, but I will post the link below. I like that there are many different colors that you can choose from.