Just a loose theory that I think would fit that place if it will be confirmed at least to some degree.
I think that maybe Ivankow meet Crocodile during his rookie years and Crocodile wasnt Okama himself but he was a deck hand, slave on Okama pirate ship

and thats how he started as pirate

Nobody is recognizing him now because he was forced to wear makeup by his capitan like all okamas of the crew, nobody beside Ivankov that probably had contacted his capitan for some reason- tea party or meeting of some kind, about Okama stuff. Young Crocodile would be painted like sad/angry mime- if I was Oda I would do it this way

How this would be his weakness or is connected to it? I have no idea
Its clear that Crocodile has connection with Okamas- Ivankov knows him, he had strong okama in his organisation as Mr 2, he has very strong pride so him being deck hand, slave on some Okamas pirate ship would be embarrassing fact. I dont think that his gender was changed by Ivankow, it would be to easy to guess for Oda.
Even Baroque Works/ Crocodiles Jolly Roger had Okama-like wings. Purple-pink ones. With two crossed swords/ spades

Maybe that points to somethung else.. we will see if Oda will push series to some more adult, tabu subjects for many.
So who knows maybe Crocodile is using his previous Capitan Jolly Roger? Or being with okamas rubbed on him in some ways
"In SBS Volume 56, a fan asked Oda why Crocodile was wearing his own clothes since he was still in prisoner clothes after he's released, Oda replied that he went to Newkama Land and got his clothes from there." just to add to his connections to Okamas.
Maybe Oda used some elements from Capitan Hook designing Sandman. Maybe real corocodile eaten his Okama capitan and thats why he named himself Crocodile, praised them- having few of those as pets in Alabasta, even had ship with Crocodile theme.
Maybe he stuffed his capitans killer- crocodile that we can see on his rainmaker. Capitan Hook from Disneys movie "Hook" that aired in 1991 had stuffed crocodile as memento, crocodile that has eaten his hand.
When it comes to Mr 0 hand, I see two possibilities- he lost in in fight with Whitebeard and gotten that nasty scar on his face in same fight or he still has it but uses hook as a standard all time weapon.