One of the first FW-190's also had a ducted spinner. It had (would you call them?) impeller blades inside it to pressure cool the BMW radial.

I was thinking...if you drilled some holes at an angle through the spinner's backplate, similar to a vented flywheel?
Or...if you look at some of the light weight Aluminum spinner backplates with all the lightening windows cut in them...you could file/shape the webs to a fan blade shape.

You could also make/shape the cowling's air exit to be a more effective low pressure area to help pull air through the spinner opening. (by that I mean more effective than your typical (seemingly ) after thought cowl air exit )