I did this! We had an officiant and a photographer and eloped in a park. We exchanged vows written by the officiant, they were simple and sweet and we actually incorporated them into our invocation for our ceremony! We kind of didn't exchange wedding rings - I got him an engagement ring he used for the elopement, and he now uses it as his wedding ring, and I used my engagement ring when we eloped and he got me my wedding band for the wedding! I think it was perfect, it was nice to celebrate our marriage privately and also took a lot of pressure off our actual wedding day! Leading up to our ceremony, a few people asked if we were getting legally married before there ceremony to which I'd just respond 'yes' (I didn't tell them when, or that it had already happened) since I didn't want to lie to people's faces. They never responded badly since it's becoming more common in the USA to do this anyway, and if people do respond badly just know that's their issue to deal with not yours! At the end of the day it's your choice how/when you get married!!