i dont think u should order extra chairs. im also having 200 or more guests at my wedding this coming june and my ceremony will be on the dance floor. after the ceremony guests will led to the appetizer table while the chairs are moved to the tables. but this is all done by people provided by the reception place.
I went to an outdoor wedding that had just enough chairs for the guests. The groomsmen were in charge of moving the chairs from the ceremony to the reception under the tent.
As soon as some of the guests saw the men moving the chairs, everybody just jumped in to help. It was all fine, and a lovely wedding.
The place i’m getting married at provides the chairs for both outside (ceremony) and indoor (reception) and they also include the set up and break down.. If that is an option where your getting married talk to them! Or ask what people have done in the past?