So yea ive found this out the other day and pretty much got it all down. to find this location, when you start off on the free explore, just go left and keep going through all teh tunnels and such and youll eventually make it to Skywatch. enjoy the grind my friends.
I find using Ether Seeds to be far more productive. Sepiks Prime drops them at a decent rate (though they're hard to find) and pop one in during an invasion on Skywatch or during the level 8 Strike. Made about 3 k in one run.