After years of dreaming, a year of fighting the persistent travel bug and 8 months of planning, I eventually put in for extended leave and now I'm heading off to travel the length of Latin America.
When backpacking through Cuba and Chile last year it became apparent to me that it was extremely difficult to experience the real Latin America in 4weeks. It also may be true that you still can't achieve that in 6.5 months, but I think you are heading in the right direction.
So the journey will start in Mexico and finish in Argentina with very little else is organised, in essences we will see... full info