= Solution
For $i=1,\ldots,n$, execute
$$
\mathrm{Load}(\mathrm{ITEM}i,\mathrm{EAST}),\quad
\mathrm{Move}(\mathrm{EAST},\mathrm{WEST}),\quad
\mathrm{Unload}(\mathrm{ITEM}i,\mathrm{WEST}),
$$
and, if $i<n$, append $\mathrm{Move}(\mathrm{WEST},\mathrm{EAST})$ before the next iteration.
Each load starts with an empty boat beside an undelivered item. Each unload leaves that item west and restores the loading <precondition>. By <mathematical induction> on $i$, after iteration $i$ the first $i$ items are west and the remaining items are east. Thus the <automated planning> goal holds after \b[$2n-1$ crossings and $4n-1$ actions] for $n\ge1$. For $n=0$, the empty plan already achieves the goal.
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