Even with visa in hand the risk is still there.
Some cranky person in your life can report the "wedding" to the consulate. The CO could also be looking at social media and see something themselves and ask for the return of the passport to cancel it.
At the POE, if you misspeak and say anything about a husband/wife they will turn you around. They have been know to try to trip ppl up to see what they would say. For example I was asked if the ppl with me was my husband. I said well we're not married yet and that was his mom. They look to see if you would just answer with an automatic Yes.
Then at AOS you start submitting evidence. They already have all your social media info and in your Case you have 50 ppl attending, taking pictures, posting on about 50+ social media sites. These posts will show clearly a wedding that was prior to your entry. Kiss your fiance good by as now your K1 was invalid at time of entry.
Is this dramatic maybe, but this stuff does happen. Heck of of our very own members went to her brother's wedding and was drilled about it.
So how much of a risk do you want to take?
Have a huge going away party, but no wedding attire, no formal attire of any kind.