Finding any more information on his work, isn't easy. I've tried, because I too have golfed a number of these courses.
I play one of his courses, that isn't listed as a credit. Odd. Especially, since his work there was stellar.
Other courses I'm familiar with have been altered with ideas as bad as bathtub ponds, green side, where a bunker use to reside. Most of these rural courses likely had little guidance after Mr. Hummel handed over the keys. i.e. No head pros etc.
I suspect Mr. Hummel was much better at the Art, than any of his course's current iterations would evidence. Too many ill-conceived changes by too many cooks spoiling the broth.
One good thing about it, the courses are not crowded.