Not necessarily. If it's as big a space as that, you could plant fruit trees on non-dwarfing rootstocks and let them do their own thing. We look after an urban nature reserve and various fruit trees have crept in - apples, plums, cherries - and all are cropping happily. Quince, medlar, mulberry and fig need very little attention. I you have a large space and a lot of trees, and you're not looking to sell, then you don't need to maximise production - just let things grow, and regard the fruit crop as a bonus.