I would love to say that I have a highly tuned vision of what 355mm on 7x17 or 72mm in 4x5 pinhole looks like when looking at a scene but I don't. I have a vague idea and as those 10,000 hours pass I'm sure I'll get better but for now...
Old school meets Modern technology. No card mask, or variable optical view finder for me. I use Cadrage "Directors Viewfinder App". It's designed for Videographers/Film makers to get an idea of what lens to use on what camera taking into consideration sensor size, focal length etc. It has a heap of built in cameras and lenses but you can completely configure it for anything.
Setting up 7x17" sensor size with 355mm G-Claron and 4x5 sensor size with 72mm was a breeze. You can add multiple focal lens to each camera and scroll through them to see have they affect the scene.