Well, this build process is really bizarre....
The structure I ended up with is basically what I started with but with the TMRpcm and QDIRRremote folders under a src folder of the sketch folder. I then had to edit the #includes in all the files below this new src directory to be relative paths from each file to the file being included..
Why on earth doesn't it simply treat the src directory as another libraries directory, and search it for all includes? Seems really goofy.
But, I now have structure that works for both VS/VM and the Arduino IDE, even though some of the include paths are goofy...
Regards,
Ray L.