A lot to unpack here:
1) There is no 90 day rule for USCIS. It’s guidance in the Foreign Affairs Manuel (FAM) for consular officials on when to assume misrepresentation in cases that they also need to be involved in, which these days mainly deals with people who entered the country without presenting themselves for inspection so is largely irrelevant. That it impacts AOS is one of the great urban legends in the immigration world.
2) Getting married can be a red flag for CBP, which is why my advice is to always say you’re entering for a vacation or tourism — this is not misrepresentation if your intent is to do a destination wedding in the U.S. and return. If you plan on doing AOS it likely is. There’s a document out there somewhere where USCIS’ internal appeals body distinguishes between “vacation” with intent to return and “vacation” with intent to adjust status. The short of it is so long as they don’t ask follow-ups and you return to Mexico it’s sufficient. @TBoneTX has a good standard line if they do ask follow-ups about if you’re getting married for how to honestly answer.
3) With all the above said, you are allowed to change your mind once you get here; the law on this is somewhat complex, but the short is that the only thing that is a bar to doing this is lying or misrepresentation to CBP when you enter. There’s a lot of myths around this topic on both the pro-AOS and anti-AOS sides which is why you see so much discussion on the 90 day rule above, people talking about if they can adjust after marriage, etc.
The most straightforward and legally sound thing to do is enter on B1/B2, get married, and head back, and then have your wife file I-130. If you do that you won’t have to worry about any of the grey areas that people waste so many pixels discussing.