The other two solutions here are correct, but I just wanted to add that you can see where the hunters are going to spawn by looking to the sky and watching where their drop ship lands. To make this easier, select the Fair Weather map effect. (This will make sure the skies are clear and there isn't any rain or anything blocking the view of the drop ship.)
Here's how I did it:
Solo: CUSTOM GAME
Map Effect: FAIR WEATHER
Extras: DIFFICULTY FAVORS MONSTER (just in case it helped)
Monster: WRAITH (but it shouldn't matter)
The achievement popped as soon as I found the hunters and attacked them. (They landed maybe 8 seconds away from my spawn.) You can quit the match as soon as you get it.
Hope this helps!