Sun Furrows Hunting Grounds

Remove and use a Ravager Cannon to Kill Machines. If you don't have the Tearblaster yet, you may use the Tearblast arrows from the
Carja Sharpshot Bow to remove the Ravager's cannon. You can also use a Shadow Tripcaster to tie down the Ravager while you destroy the Watchers with the cannon to save yourself the trouble of killing the Ravager.

An alternative is to override the Ravager if you are able to. Whatever the Ravager kills will still count but this method also means you don't have full control of your time in the trial since Ravagers can sometimes take their time when it comes to killing.

Remove a Thunderjaw Disc Launcher to Kill Ravager. The same strategy can be used on the Thunderjaw as with the Ravager trial. Remove the disc launcher with some Tearblast arrows or the Tearblaster.

However the best and quickest approach seems to be overriding the Thunderjaw. However you'll have to have completed the Cauldron ZETA to gain knowledge of overriding a Thunderjaw.

Override Ravager and Kill the Thunderjaw. The best and fastest way to do this is to sneak around and override the Ravagers. Once both have been overridden, remove the Thunderjaw's weapons and use it against it to deal a huge amount of damage. Strike for its heart component to deal maximum damage. Having Skills Concentration +, Fast Reload, and Triple Shot will be vital for dealing maximum damage to its heart.