Possible Clues:

• 'Where one might be in the van, but not for leading attack (2,3,4)'
• Never in the van
• Towards the end, a sailor holding present..
• Where to see a caboose
• A sailor going round that place behind
• In front of the army, back of the train there
• Van on the train, but not in the army, there
• A sailor therein - abaft
• Aft
• Back there in a tar