B would be no option in my opinion. if you think of the theoretically possibilities like playing with a joystick you can't put the phone on a table without any special mounting.
Also I would consider it only if it would shrink into the OH (unlike your render) that would result in a really thick OH.

How would a construction of A/C/D look like? You also would have to have an OH thickness as wide as the R232 or your OH go around the phone on all- or only the upper side(s). Did you think of this idea?

One more effect to consider is the one on the bags for jolla. The only possibility to maybe not break every already existing bag is A. Then only the thickness can still be the problem.
Thats the reason A would be the one I vote for.

Mentioned before and now asked for all options. Are you planning to shrink it into the OH or put it on top?