Philtpads might be the answer for a large number of pipe smokers who have problems with excessive moisture, tongue bite or packing too tightly.
These chalk inserts, with ridges down the sides, fit into the bottom of the chamber, and tobacco is packed on top. The chalk will absorb excess moisture, and the ridges allow for better airflow. At less than $2.50 for a pack of 10, it's worth it to see if they can solve your issues.
Note: Philtpads can be reused, but they should be removed from the pipe and allowed to dry thoroughly beforehand.