You need to InstanceTimer or similar Farmer addon to find out how fast your xp/cp rate is.

Some people grind the merman fishing village north of Nagle, but you need enough dps to get it to hyperspawn sadly other people might be doing the same. But crazy multiple hyperspawns are possible.

I would expect the monkeys to work, even if you cannot aoe them down, you should be able to grind them pull by pull.