I've been using one in the meadows. No need to dig. Just build a few floor plates over the spawner to protect it from your skeletons hits.

Strongly recomend cycling skeletons until you have two archers. This method works okay up until about 50 then it's a pure slog. But at 50 the skill gets pretty good. Also helps if you stand between the archers and incomeing damage to tank with your own shield. You do not get exp from the skeletons taking damage.