I never done it on horseback(I found it more difficult and I lost each time tried on horseback. (52 times if ur wondering) But the 1st time with the tactic VembersWind is describing I beat it no probVembersWind you do realise your supposed to do it from horse back right? that means you make Epona run through the grass and the grass gives up arrows, meaning you don't run out, slowly down time really helps, and 'They' are infact just ghosts and therefore from deduction a type of poe.
This is a good tactic it's 1 that I use all the time when this mini-game/quest.I found a much easier method. Find the gap between the barn and the farmhouse. Stand out in the field in such a place that you can see between the two buildings since one of Them will come around the back of the farm house. As long as you don't waste arrows trying to hit targets that are too far away (you'll have to hit one way off on the side, but it's not really a difficult shot), you won't even have to move, making this battle an easy one. Wait for them to get close to you and strike.