I messed with the C++ exiftool interface a few weeks ago, to the extent that I had to submit an issue to Phil Harvey, which he promptly patched in exiftool (11.82). There is one thing that API doesn’t expose, and that’s the tag data type. I developed a patch to include it, but Phil thought it was a bridge too far for most users of the API.
So yes, I think that API should be compiled from the source. And, you need to use exiftool >= 11.83 if you’re going to use it to extract binary values. I’m presently working on exiv2 incorporation in rawproc, will look at exiftool incorporation after that.