The good/noble savage illustration
CONTAIN SPOILERS
A noble savage is a stock character, a stereotypical character who embodies the concept of an outsider who's mind has not been corrupted by civilization and symbolises therefore humanity's innate goodness. This was first used by John Dryden, in his play The conquest of Granada, used in reference to thenewly created man, but then became identified with the idealized image of "nature's gentleman", an aspect of 18th century's sentimentalism, which is the belief that the difference between moral and immoral are discovered by emotional responses to sexperiences. It represents the idea that in a state of nature, men are filled with natural kindness and innocence, lost with the apparition of society and commercial relations, for example. This state has been defined wrong by civilization, who attributed the word "savage" to this way of life, with the negative connotation of the absence of manners society is supposed to have brought, as it was done to native Americains.

Unfortunately, in his will to achieve his lofety ideals, he fails to grasp some basic truths about living in the wild. Indeed, seeking nature's beauty, he forgot that the most important in nature is how to answer human's basic need, in other words: to survive. As he enters the wild, the guy who gave him a drive to this point sees he is not prepared enough and has to give him boots to keep his feet dry, as he didn't think about it. Also, while living in the wildness, he had not decided if he would stay a long time or not but still, it is a well known fact that to have enough food it is necessary to stock it, especially when you think that if there is a lot of game during a season, it will leave afterwards. By not being providing enough, he ended up starving in the wild lacking food, which leads us to the last example, his self-poisoning. Of course, it is comprehensible that starving and barely stable mentally because of it, he made a mistake identifying the plants he could eat with an inedible one. Though, coming into the wild, if he had prepared his stay well enough, he should have learned long before what he could eat and what he could not, knowing the unstability of the game's presence, it would have been normal to learn the utility of plants. So, what it failed to grasp was in fact simply the dangers of nature, that he underestimated, blinded by his expectations.
As I said before, i don't think Chris can be qualified a noble savage. Though his ideals are in accordance with the caracteristics of the good savage, his propension to only search for beauty in life, through books as well as through his life in the wild would place him more in the romantic category, which besides side up with the myth of the noble savage about the consideration of nature, the will to return to the forgotten sources of life. The thing is that Chris's convictions appeared because of his previous life in society, and his feels for his parents, which is in contradiction with the idea of the good savage and reveals more of an idealistic way of thinking. The influence civilization exerced on him can be seen as he finds the magic bus: he wanted to get away from material binds, but finding this sign of civilization with usable ustensils made him happy and he decided to use it, for he was accoustumed and in need for some confort.
Going back to a State of nature once one has lived in society is, in my opinion, difficult but possible.
Indeed, for a lot of people it would be impossible to deal whithout basic material comfort and to survive outside of societie's barriers. Though, there is also quite a lot of individuals who cannot bear civilization and it's restrictions, and that would like to run out from the rotten world they see growing around them, as Chris does. For these people, it would be possible, but they would need to be way more prepared than Chris was, to be aware of the price of leaving society. Also, as Chris dicovered too late, they should not leave alone, for "Hapiness is only real when shared". There are people who like peace and loneliness, but eventhough to live in the wildness, far from societie's surveillance, it would be indispensable to live at least close enough from each other to receive help in need. If society as they see it is today wicked and twisted, the basis of it were to unite humans in order to survive by helping and supporting each other, without any consideration of power or wealth.
To conclude, I can't say if it is advisable, for it depends on people's thoughts, but as it is possible, I would say it is advisable to follow your convictions, and that if someone think going back to a state of nature would be a good thing for him, as long as he is aware of the dangers and takes them in consideration, it would be advisable for this person to try this life style.
So, if I had to prononce myself about Chris McCandless's decision, I would say that despite his few mistakes, Alexander Supertramp was Rigth.
The Mad Hatter