Late on the scene here, so I can't really add anything that hasn't already been said, except a ton of admiration for your command of the multiple layers of inspiration, lyric-writing, music-writing, arranging, vocals, real guitar playing (sometimes), mixing and mastering. And you are able to create such a live studio sound with your choices and technical mastery of instrument mixes, shots, holds, etc. Lot's to learn from you bro'.
I am using BIAB on a MacBook and GarageBand for mixing, so I am not sure what you mean when you say you added BIABetts to the vocal mix. I do recall in RealBand on the Windows platform there was a feature to modulate your own voice into harmony parts, but RealBand isn't available on the Mac.
Anyway ... great song, great production, and like just about everybody here, I am a bit fan of the Eagles, and intentionally or unintentionally, you nailed that early Eagle's groove with multiple guitar tracks (Hotel California has 12 I believe) and those great vocal harmonies. Thanks!