Instead of push-buttons, use pivot buttons(sorta like how digital volume buttons are in car stereos) for the shoulders. You would double the micro switches per button and allow someone to "pull" for L1 and "push" for L2.
That's so much better than my crap pic here.. I have had terrible trouble trying to get this up at every point - and considering that we've had a pretty solid no on the matter, I didn't put too much effort in this after all. Don't take this as gospel more of an idea that could be implemented better still. I would have drawn them higher, but this way it is basically what they showed us with a bit extra underneath.. The text basically says-
One shoulder per side, 2 actions. Perhaps viable without the overhang at all depending on how much of the above space could be used for them. The slight angle would maybe help 2 ways, using the keyboard on a flat surface and giving something to rest your fingers under while holding with one hand, and using the stylus with the other..
A finger indentation slightly biased towards the top (L1) switch and slightly curved around the side and maybe back of the unit.
The size of the buttons only depend on how much of that upper back area I left blank could be covered maybe if you don't like the idea of angle and overhang the actual dual in one shoulders can still be used without it.
Anyway, we can probably forget triggers like my old pic because it just wouldn't work on this type of design we have now. Well it would
work, but the unit is too small to accommodate them really.
Thanks for listening, I will put this to bed now it never was supposed to be selfish, I truly believed that this would actually help sell it. I can live with 2