In case anyone's interested: I ordered one of these.
https://www.etsy.com/listing/1022749...case-wallet-7?
I prefer to read it without the heavy sleepcover, and these are a nice fit and do feel like they give some protection when I carry it around in a bag like that.
Although I admit it's not too difficult to detach it form the sleepcover, so you could still simply use that to carry it around in and detach at will.