But there is one thing to consider before all of the discussion here: why do you think you'll be able to make money with you game? the vast majority of games here make far less than 100$ a month. There are a few outliers making big bucks, but also a long tail of sad developers.
There's another thing to consider, that come even before that one, and that is way more significant.
OP fear that if someone study his earning too deeply, he'll be uncovered as making an adult game. While I find this disproportionate, I can understand it. But at no time he considered what would happen if he use parallel circuits to get his income.
On one hand, there's the basic dev. He have a Patreon page, and Patreon send the money directly to his bank account:
"Hmm, those sums you got monthly, what are they ?"
"Oh, that, it's said, it come from Patreon. I have a small hobby, and apparently there's few guys who like what I do and decided to help me."
"Oh, Patreon, yeah, I know. It's a big company, they follow the law. They even enforce their prostitution bans and have strict rules regarding their content. Well, I guess that covered everything, you're good to go."
On the other hand, there's OP. He have an account somewhere and, while passing through a lot of intermediaries, in the end the money reach his bank account:
"Hmm, those sums you got monthly, from that really suspicious source, what are they ?"
"Oh, that, er... It's nothing at all, just some guys who like what I do and decided to help me."
"And they can't do it otherwise than through that weird circuit ? Never heard about crowfunding or patronage platform like Patreon ?"
"Er..."
"So, please, tell me more about that money... What are you effectively doing to get it ?"
Even if he achieve to found a way for the money to never go on in bank account, the money will still end in his hand, and he will spend it. Someone who would starts to study his earning too deeply will not limits to looking at the income, he will also look at the expenses. And he will not limits to numbers, he will also look around him.
"Hmm, so I see that you've an average salary. Not too low, but also clearly not the kind that permit you to life in such neighbourhood. A bit above your earning, isn't it ? So, tell me, how do you afford to pay the rent ?"
Using an indirect way to get your money will never fully protect you, and will always raise suspicion the instant someone will starts to look at your incomes.
Someone who would looks and see that the money come from Patreon would at most look what Patreon is, and once seeing that it's a big and well known company, that serve more than 200,000 persons, there's 95% chance that it drop the subject. But someone who would looks and see that the money come from a suspicious source will want to know more 100% of the time, and will not drop the subject until he get a satisfactory answer.