i dont understand the question.
the stofen is really designed to spread light, if its tipped upward it will bounce light off a ceiling, if available, without a ceiling it will taper the light, diffusing upward if it is tipped in that direction. if you want minimal shadows you need to minimize, or compensate for, or fill the shadows created by the primary light source, presumably the sun. that can be done by shortening your shutterspeed to compensate or limit ambient light whilst adding flash to fill the shadows, or while strictly adding ambient like with a reflector fill) or flash (upto your desired setting's) whilst keeping your shutterspeed and aperture constant, and usually from as large a position above you lens axis as possible in order to fill and eliminate shadows equally, to the desired ratio.
does this make sense?