You might try roughing up the back of the masonite with sandpaper to get better adherence.

Hide glue is a traditional approach that takes a little work: you soak the glue pellets, heat them to 140 degrees in a waterbath and then apply. The benefits are that it tacks very quickly but is initially repositionable, is reversible through reheating (though this might not be easy with a photo involved) and cleans up very easily.