Couple those with either the Range Master or Powershots valor surge and anything dies a quick death. Depending on your coils on the bow and your armor, you'll be taking Tremortusks out in 2 hits. Even without the valor surge and a low effect sharpshot bow you will deal major damage at distance. It does use a bunch of stamina and doubles arrow usage, but it is extremely effective

Now, as far as which sharpshot bow, that depends. You'll get one as part of the main story, and you can find another at a camp. Those will hold you down for quite a while. Once you get closer to the endgame (or grind in the arena) you have a few other options. I've got the Glowblast bow, which is one of the few bows to use tearblast arrows. Stupidly strong, but needs all the greenshine to upgrade, so get ready to clear those sunken caves. I recently got the Forgefall, and it can be devastatingly strong, but the grind to upgrade that one is pretty high