Michael Dimin is excellent, plus there are two chord books worth checking out. Either of these books will teach you more than you will ever need to know on that desert island. Or if you stay there a long time and master one or the other books, when you are finally rescued, you will be a chord demon and even Michael Dimin will be impressed...ah, but maybe not the girl.
Chord Studies for Electric Bass by Rich Appleman and Joseph Viola, Berklee Press
The Bass Chord Method by Jeff Berlin
I'm sorry, I can't find my Berlin book and I had my hands on it just yesterday. The name I gave you may not be exactly accurate.
You may be able to find these books at:
www.bassbooks.com
I checked my "Bass Grimoire" which is an encyclopedia of chords and scales. There is no "funk key" listed and I have never run across one. However, you are not the first person to ask that very question here. I remember that same question was posted here a year or so ago.