Not sure about licensing and all that but any chance of updating to FDKv2?
https://github.com/mstorsjo/fdk-aac/releases/tag/v2.0.0
Not sure there have been the same updates to their FHG encoder
I know Stax has QAAC
https://sites.google.com/site/qaacpage/
But not sure how they get around the iTunes being needed.