I compared the images I posted with your (new & improved) stick figure. Pretty close except for leg length/inseam differnces. My knee joint is above the engine frame, where the stick figure's knee joint is well below it with a more pronounced bend in the legs. Same with my arm length.....
Soooo.... I was thinking,
you might ask that the rider to enter an inseam measurement
- or -
have the rider choose one of a few body types like maybe
a long & skinny body type, or short & fat, "normal", and a big boned thick/muscular type.
(Lemme know if those images I provided helped you atall; ....I would offer a side view with my legs extended toward the ground, but somebody would have to hold the bike up for me 'cause I come nowhere near being able to reach the ground while sitting straight up over the center of the bike....... just can't do it.)