I found a nice spot that looked like it would work great for grinding. Normally, I wouldn't want to reveal it, but nobody seems overly interested.
Solo or in a group, if you head out northeast from Camp Bloodshore, there's an island that extends off the mainland. On that island are a large collection of Bloodshore Bells, jellyfish. They were red/orange/yellow to me at rank 14. Hit fairly decently, but I could still solo them reasonably. I imagine if you had a group, or just a duo, you'd do pretty well. The other nice thing is that since it was out of the way, I only ever saw one person hanging out there, and there were more than enough of these guys to go around.
Just a thought. If you do look into it, tell me how well it works for you. Nobody I ever group/duo with seems interested. They just want to do the typical Dodos everywhere (super boring!)