The reason why Esav was found worthy that his head would enter the place known as the Maaras Hamachpela, was due to the fact of his massive respect towards his father in the area of Kibbud Av V’em?
But why specifically his head? Is their a particular reason for manly the head being on the that territory and not the whole entire body? In a way, Kibbud Av V’em was most probably done with his whole body, rather then being singled out as just the head. I’m assuming that, maybe because he was wicked – so his body couldn’t take part onto that ground like a holy person would’ve. I’m not really so sure why.
What you are saying that the reason that Esav’s head was buried in the Maaras Hamachpela was because of his Kibbud Av V’em is brought in the sefer Mitzpe Megadim pg. 202. I once heard that the reason is because the mitzvah of Kibbud Av V’em is the most basic intellectual mitzvah, that a person should give recognition and be thankful to those who took part in creating him. Esav was a very big person on an intellectual level, his problem was that his body and heart had a hard time accepting the mitzvos, therefore his head, which was very big, made it in, but not his body. I understand your point that the actual doing of kibbud av vem is with the body, however it really starts with the mind, and the intellectual understanding of the need to repay our parents for what they have done for us. The Maharal (Tiferes Yisroel 41 D:H Amnam) says that “Dama Ben Nesina”, the gentile that did Kibbud Av Vem, that that was not his real name, rather the name of the reason behind why he honored his parents so much; Dama mean obligation Ben –because “Nesina” for what was given. Since Kibbud Av Vem was a very intellectual mitzva, Esav excelled in it.