(1) IMHO the kidney-bean problem in the 8x32SE is not solved by getting the correct eye distance from the eye lens. You can get the perfect eye distance via extended eyecups, or an appropriate hold (more below), and then this: gently and naturally roll your eyes in the field of view and see prominent, distracting, black edges.
(2) I use binos pretty much daily simply to enjoy views, switching among: Nikon 8x30E2, Fujinon 8x30FMT-SX, Leica 8x32BN, Swarovski 8x30W porro. Easiest/quickest eye placement is the E2, followed by the Fujinon & Leica about same, with the Swarovski slightly finicky on initial eye placement. (But if I could keep only one, it would be the Swarovski.) Anyway, in each you can gently, naturally roll your eyes around the field of view and enjoy. Not so in an 8x32SE.
(3) In that respect I find the 8x32SE quite unnatural and soon tiring. Sure, I can “relax” my eyes toward the centered field and appreciate its truly spectacular view. But that “relaxing” soon turns to tension, as it is natural to slightly roll the eyes when viewing, and then one sees a lot of black.
(4) Some years ago I requested here confirmation of my impression that the 8x42SE is much less prone to this problem. Kenny responded with his usual eloquence, “Yes.” In my 8x42SE I experience negligible kidney bean and enjoy this bino tremendously. Vaguely I recall that Nikon first issued the 10x42SE as a pure tour de force, an ideal. Soon after came the 8x32SE as a follow-on ... all same optics except objectives. Maybe that necessitated the compromise of worse kidney bean.
(5) IMHO with small porros, to get best eye distance, we should not be modifying eyecups etc. We should learn how to hold them. Have a look at Hold #2 at: http://binocularsky....binoc_hold.php.
Fingers around eyecups give so many benefits regarding stray light, contrast, eye distance, and steadiness that translates to resolution. I venture that daytime with a small porro Hold #2 adds about $500 worth of optical benefit.