Pack it out with Selleys "KNEAD IT".. wonderful stuff. Have bogged up a broken flipper before with this stuff... worked a treat!

+1.  Knead it would work, sets like a rock.  It might pay to rough up the interior surface of the trunk a smidge with some fine sandpaper to give the knead it something to hold onto a bit better as opposed to a smooth surface which it can peel away from over time.