With sneak 5, I remember I was able to go to the firing spot. The wolf are strangely not perceptive (very low detection cone).
Other solution is to do it with scoundrel skill "walk in the shadow" or with an invisibility potion. Either way, it lasts 5 turn which translate in at least 30 second of invisibility. This is plenty to either fire or go through the cone detection area to a safe firing area where you can sneak for as long as you need. After the initial hit, use tactical retreat skill or if you can, sneak again.
If not possible, the opening with the oil barrel teleport is just as good because the burning oil generate smoke , hiding you from their archer. You can't kill them instantly as the previous solution but they won't be able to fire at you on their first turn if you position yourself well. Then, they will move to a tiny spot where there is no smoke and will likely sitting near the skelly bomb due to the artificial bottleneck.
Either way, It should be easy to get rid of them.
