If some of the nipples are hidden in the rim, then I don't understand your problem about having too short spokes.
The spoke that you're holding in the photo should be able to reach the hole if you simply pull the nipples on the opposite end through the holes completely to expose them. The problem if they are hidden is that they get stuck deep on the inside edge of the hole and pull the hub further away from the opposite side where you're trying to lace.