Hello ChurnOwl -
To get the full field of view, you'll need your eyeballs (not facial features) positioned sufficiently close that you can see the field stops. Meaning the sharp edge defining the entire potential field of view. The height setting for adjustable eyecups can differ for individuals depending on the geometry of said eyecups and faces.
With wider, adjustable eyecups, I always brace against the bottom of the brow ridge. I understand this could be uncomfortable for some, but try using less pressure. Light contact should be sufficient.
Or you might try using the way I hold binoculars most of the time when I need the steadiest view. Support the tubes or prism housing lightly on the palms, extend thumbs and forefingers, and place those against cheek and forehead. Plus contact with brow ridge. This pretty much eliminates hand tremor as a factor and only body/head movement remains. I have done this for decades now - since 1970s actually, and it works very well with all types and sizes of bins.
Fold-down eyecups tend to be smaller in diameter, and those I place farther into the eye socket. Since I never wear glasses, I find those work just dandy for me. I never experience the blackouts with SEs that some have, and really can't say why.
Good luck!
- Bill