First some clarification for me, as I have not heard of a “smart view case” before and did just some online search. It is a case, where some part of the screen with important information (clock, messages …) remains visible; right? The cover can have a plastic window or simply a “hole”.
Have you already seen this (rather lengthy) topic:
While I doubt, that there is a smart case mentioned in the thread, there are some cases (slip and flip if I recollect it correctly).
Maybe you could take one of those and simply cut the window you need with a carpet knife.
Probably the “Feuerwear” slipcase could stand such a treatment (maybe the cutting needs to be “stabilized” by some glue or other means?).
But there are other cases as well of course, that might work.