Then I don’t see a problem. And realistically having backup for rb is a good idea as rb’s future is atm quite unknown.
What you can do is have both. Do the thread on RB, and others can, even if they don’t check RB regularly, get in a FB group. When a new swap is being organized, someone can just drop a link in the FB group and everyone will be able to see it.
We can try with the RB Refugees group for example.