Have you thought about adding another texture flex to your models L.A.? What do you think about adding a frown texture flex?
Actual wrinklemaps are nontrivial to author and not have them come out looking hilariously bad. Proper ones require normal-maps as well, which are not only nontrivial to author but are also very technical, as they are not actually colors like diffuse maps, but instead use the colorspace to define angles to deflect light at.
That is something so far outside my wheelhouse it's not even worth entertaining the thought of.