Glad to hear the rangers are willing! Here are the clues you asked
for:

Cape Henlopen Tower Letterbox
Placed on August 7, 2002, by Daphne's Family and Lizzy
Replaced December, 2002.
Cape Henlopen State Park, Delaware
Enter Cape Henlopen State Park and obtain a park map at the
entrance. (Parking fees are $2.50 for in-state vehicles, $5.00 out-
of-state.) Follow map to the Observation Tower. Climb to the top of
the tower and, after enjoying the view, look south along the coast
toward twin towers in the direction of Rehoboth Beach. Facing that
direction, look down to your left and locate the paved bike path that
appears to lead in that same direction. Follow that path. In a
short while, you will come to old railroad tracks embedded in the
path. From these tracks, count 25 (adult) paces. Directly to your
left, you will see a large, gnarly pine tree, the Guardian of the
Letterbox. (If you come to a fork in the path, you have missed the
tracks.) Search no higher than your head for the treasure it guards.