I have 100 year old apple trees but I also have a 40 foot long extension pole from my janitorial days. so I can reach some fruit for fresh sale. The picker has a wite hop and a cloth bag. where the wire comes together at the handle that screws on the extension pole is a small pruner that I can pull a cord to snip off the stem.
The original poster it seems is asking for theoretical ideas for a permaculture plan that avoids the problem without machinery like is used in modern spindle pruned orchard that uses a wagon with a lift with 2 men on each side and storage for the picked apples in between. It is also used for pruning in the winter time.
The point is plant and train the trees according to your harvest plan. Can you terrace a hillside so the top of the tree can be harvested from the terrace above? Young fruit tree growth is easy to bend so train it for easy harvest as Red Hawk suggested. one of the old trees had a branch a foot in diameter and 20 feet long and 10 feet up which shaded windows in the summer. You could open the windows to harvest the fruit. It failed in a snow storm because of poor management in the past. Some one cut large branches off at the top so the center rotted and was eaten away by wood borers. The tree still lives on as a hollow trunk with a small tree at the top.
I think the ideal tree is a huge fan shape at the bottom and then a single center leader that is allowed to reach the trees natural height but not width of branches. when a tree has its natural height pruning it back produces less sending up vertical growth to try to restore the lost height when pruned. This results in having many easterly reachable fruit and only a few high ones
For more Ideas go to Fruit Growers News
to see the orchard designs and machines that have been developed to answer this question.
Harvester described above