You might want to look at Robinson Crusoe through the lens of Foucault's "The Birth of the Asylum" from his book Madness and Civilization. Most histories of mental illness and insanity see a straight line from barbarous treatment of the mental patient in the Middle Ages to more humane treatment by the nineteenth century. In the Middle Ages, the mental patient's body was chained up; by the nineteenth century, the body was usually unchained while doctors worked on curing the patient of his mental illness.
Rather than see this as "progress," Foucault argues that the insane person in the Middle Ages was actually treated more humanely than later on: only his body was imprisoned, while his mind was left free. Foucault sees the efforts to control the mind of the mental patient and, moreover, the measures taken to ensure that mental patients would internalize bourgeois norms and self-regulate, as steps backward. He looks at institutions run by Pinel and the Quaker Tuke as more repressive than anything the Middle Ages produced.
How would this apply to Robinson Crusoe? We could understand him as in a sense "locked up" on the island. It is a place he can't escape and where, as in Tuke's Quaker mental hospital in York, England, he is isolated and forced into self-reflection. After a period that we could designate madness in which Crusoe for a short time cannot cope with being alone on a deserted island, a self-regulatory internalization and adaptation of bourgeois norms take place.
It could be argued, following Foucault, that Crusoe is not free on his island because he is so dedicated to a disciplined, regulated life of carefulness, frugality, planning, and hard work and that he has done this to himself by internalizing the repressive social and religious norms of middle-class Protestant society. Everything he values about the island he now lords over, such as his stores of food, could be seen as signs of his chains.
A good way to understand this would better be to look at Michel Tournier's 1967 retelling of Robinson Crusoe called Friday that does, interestingly, recast Crusoe as a Quaker. In this version of the story, rather than control Friday and teach him to behave like a European Christian (though he does try), Crusoe is able finally to learn a new, freer, and more joyous way of living from Friday and cast off what Foucault would call the shackles of internalized bourgeois values.