Reminds me of "The Wrong Way Home" about a guy who did a similar land-only trip, except from London to Sydney.
I spent a huge part of my teens and early twenties dreaming of doing the same. These days the mere thought gives me a back ache.
Still exists, without a book to talk about it. Travel is cheap and my lesson is that every sleeping condition is acceptable, provided it’s temporary. A friend came to see me in Sydney, from France, using hitchhiking. He loved Kazhakstan and central Asia, hated Vietnam (which I loved), and took a flight from Singapore to Pearth. Western countries are the most boring, apparently.
I did the exact opposite of this in 2011 and it was the easily the most memorable 3 months of my life. Takes some planning (mostly making sure visa dates line up) but it is an incredible experience.