Not damage stamina, just haki stamina is all that would need to be fixed for G4 Luffy to beat Dragon Kaido. Boro breath isn't hitting Luffy without Big Mom's distraction.
Kaido won't be having this fight against the SNs for 3 days so that's not true, the extended fights only happen off screen lol.
We are imagining an expensive hypothetical scenario.
We saw that KAIDO vs BIG MOM lasted 3 days.
Luffy unable to kill kaido mortally in the G4 can endure 3 days of fighting DRAGON kaido without getting exhausted?
You will lose your HAKI and will be extremely exhausted because kaido will not give him rest, luffy does not defeat dragon kaido, the weakest form of KAIDO.
In the end KAIDO after leaving Luffy exhausted and without haki, he returns to his human form, and defeats him with a single blow, his divine diagram.
He will not be taking kaido to a 1x1 hybrid.
Luffy is weak compared to kaido.