I made this Coarse Leather farming guide to help out players who want to farm the leathers instead of buying them from the Auction House. I traveled around Zuldazar and Kul Tiras to search for places with high density of mobs which I can kill and drop Coarse Leather. Below you will find a list of places I think are the best for farming Coarse Leather.
Invasive Quillrat at Hawthorne's Plot will respawn very quickly, you will never run out of them.
There is always at least 3-4 Vicious War Crawg at the marked area, you will never run out of them.
TomTom coordinates: /way Nazmir 47.29, 55.45
There are is always at least 4-5 Scavenging Boar are up at Hocking's Plot.
Kill Da'kani Pugilists and other gorillas around the marked area.