Jeez people, you don't need a specific "secret camp" or tricky method. Just go out to an Adoulin area that has monsters in it. Kill them fast. Set appropriate RoE quests (crystals! mob types by zone! multiple kills!).
The best camp is just one that isn't overcamped by other people. Which is the reason nobody wants to tell their personal camping spot, because fools who can't think for themselves will just come camp right over you (and ruin the exp for you and for themselves) instead of going to any of dozens of other spots with comparable exp/sparks per hour and nobody camping there.
Remember merit parties? It's like that. Just keep moving and chaining/killing fast, with a party you'll probably have an unlimited chain (even solo on PUP the other day I had a neverending chain for the entire ~1 hour I was playing and I got lots of exp/sparks). But it's better than merit parties, because there are lots more camps than a few high level pink birdies in an area that supports only a couple parties. Your only real limitation is amount of mobs, so go grab your own little corner of the world and kill all the things.