"I Wish they had made a Mike4-to-Mike3"

You mean like this ?  ;-)

(The other is my weightmapped Mike4-to-David 3)

Sorry, can't distribute him as DAZ are stricter about the V4/M4/K4 mesh than they are about the 3rd Gen mesh.

It was a bit complicated to make him, but as you see, not impossible. Don't know why DAZ never made one. Maybe the same reason there was no David-4 or a Luke/Laura-4. Simply not worth the effort.