There's a lot of ways to do this.

One way is to place a symbolic link to the header (or header directory) in the Strategy folder. So you can do this in your script:

Code
#include <symlinked_extraheader.h>
or this:
Code
#include <symlinked_folder/extraheader.h>
For this, you will need Microsoft's mklink command, which is documented here:
https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/mklink