Since this is a group thing, I might have an idea or two on how to avoid it being just 1x1
Since it's just starting, have a meet and greet so that people meet one another.
You can also have mandatory group sessions, where all the doms gather together to speak of their experience in a constructive way, and all the subs meet separately for the same. Meetings would happen a different times (but RPied simultaneously) at the end of each day?
I thought about joining, but I'll wait to see how it goes and if there's something missing to make the ratio equal.