This post almost didn't make it. I have a very difficult time looking at myself in this pose. I am usually fairly accepting looking at pictures of myself, but these in particular were difficult. Maybe it's the angle, or the pose, or the extra weight that has crept on this year; it doesn't matter the reason. This is who I am, and this is useful work in Malasana.
You may have tried the following variation of Uttanasana. This really stretches the calves.
Now, try bending the knees, bringing them forward like they would be in Malasana. This really changes the stretch for me, and I think it gets to one of the difficulties I have in Malasana.