"D Tune" could be about love and separation. Perhaps some references to the Chinese concept of ying yang. Also during Robin's lead guitar parts, maybe make Axl's voice match the lead guitar melody?
"Zodiac" would be perfect in Axl's "Shotgun Blues" voice during the verse and in his mickey voice during the chorus. Maybe a song about society driving you insane?
"Tonto" could be about time running out. Life passing you by and wasting it away. It could be like a "I fucking you told so, but you didn't listen" type of song.
All this sounds interesting though. I'm down to help out! 🎸🎶