Matthew,
My wife does not eat red meat so I make meatloaf with ground turkey which can be a bit "dry". I have found that adding a large portabella mushroom to the mixture gives it the moisture. I cut off the stem and then remove all the gills. I then cut the mushroom into 5 or 6 pieces and put it in the blender to finely chop it. Add this to your meat mixture and you will get added flavor and moisture.
Ray