Going K1 route is already not the norm. Hell, even going spousal route is not the norm. The norm is to meet someone in your vicinity, plan a wedding for 1+ years, spend 10s of 1000s of $ to hold the event. In our situation, you have to do what time and means allow. Time and money is a huge factor. Nothing wrong with a UPS marriage and worrying about the celebrations later.
To OP, you are fine to do this. A marriage cert is a marriage cert. If your relationship is genuine, there will be nothing to worry about. But it would help your case if you do something that includes both side of your families and can document it for AOS purposes. Also, bona fide marriage is not evidence through a typical wedding ceremony, or lack there of, you need to think about everything, normal life, beyond the legalities of marriage.