ignore the blockage & compose in your mind
one thing i've relearned with switching back to a rangefinder is that when I'm looking for a shot with the camera down, I'm looking for interesting subjects in scenes. Before i raise the camera, I have an idea of where I want to place the subject in the scene, so I immediately raise the camera and place the subject where I want, usually on one of the 1/3rd points. I find it very unusual for me to want to place a subject\main focal point deep in the corner of a frame, so it's not a big deal. If you're more into shooting scenes than specific subjects or focal points, you'll struggle with this blockage.
Once you learn that, it's even possible to use a ~.68X viewfinder to shoot a 21mm. Just tuck the subject into the corners of the frame of the 28mm framelines. Here, blockage of the 21mm lens in the 28mm framelines becomes a little more important.
having said all of that, i dont own the ZM35 1.4 but I am very used to composing with the 28mm cron with the stock hood and the 35mm summilux hood on a .68X.