I use a 5" silicone spatula. Lay ten baits across the spatula, use about four drops of worm oil inside the bag, insert the spatula inside the bag, with the spatula still inside the bag, turn the bag over and remove the spatula. Walaa.
If the spatula is a little wide for the bag, use a grinding wheel to knock off the sides a bit. Once you get this thing dialed in I think you'll find your bags filling much faster.