Rush,
Your post about fitting Earl Derr Biggers' Charlie Chan made me realize about setting such a movie today: The current politically correct attitude on, for lack of a better term, the physical aesthetic movement towards getting people as overweight as Chan to get his weight down.
For his own good now!
So if he can't LOOK like Chan then he would HAVE to be a Martial Arts expert to have SOME kind of hook or be boring as all get out.
IMHO.
So setting Chan anywhere from the 30s through the 50s might be better than we might think.