I told everyone about my health problems and asked for their help. See my poem about the event "Good Neighbors" at my blog http://sherryannestories.blogspot.com/
That took care of the food and physical arrangements, but how could we make everyone feel comfortable and welcome? We just deal with one or two people at a time, not 50 at once! I found out that it was true. I did get tired and was not able to be the charming hostess, but I also learned that I didn't need to be all that outgoing; all we had to do was invite some people who were and we did. We knew that about half of the people were quiet like we are (normally intoverts are only a quarter of the group). We also knew that we had at least four strong extraverts, one of which was a take charge doer (SJ sensing judging).
On the night of the social, I anxiously waited to see if all would work out. Everyone came wanting to make the evening a pleasant experience for all. The SJ's helped set up, cook, serve, and clean up. The extraverts greeted everyone and warmly visited. Initiatives sensed what needed to be done and did it, and introverts talked quietly in small groups. We all had a great time.
I learned that a large social is actually easier for us. It allows those who are more outgoing to help carry the social load. Healthier people can manage the details and introverts can congregate talking in small groups. Together, our variety made an enjoyable social.