If the truck can carry 1000 apples at a time, Bananaville is 1000 miles away from Appleland and you pay one apple per mile, then it's impossible to deliver any apple to Bananaville, because on 1000 miles you'll pay 1 apple * 1000 miles = 1000 apples as a tax. So no matter if you go once, twice, three times or a hundred times there - you'll be never able to deliver any apple.
Answer: The highest number of apples you can get to Bananaville is 0.