Good co-op level for late Liurnia and early Atlus?

Bout to head to Caria manor, and then Ruin Strewn Precipice. Currently RL 40, WL 5(2). I've read through a dozen old reddit posts and I can't find a good answer. I guess I want to be summoned by people in late Liurnia, early Atlas, and Caelid (Redmane castle). What do?