Well, more of a guide than route.
If you imagine drawing a line from each of these places it would give you an idea of the route,
Buenos Aires - Argentina
Ushuaia - Argentina
Santiago - Chile
La Paz - Bolivia
Lima - Peru
João Pessoa - Brazil
Rio de Janeiro - Brazil
Montevideo – Uruguay
Buenos Aires – Argentina
I will stick near to the coast so I will travel round the outside of South America till I reach Peru. I will take the BR230 or Transamazonica as it is better known across Brazil to Joao Pessoa and then again continue down the coast till I arrive back at my starting point.
I have no time schedule to keep, other than a limited time in each country due to visas 3-6 months. I will apply for a longer stay in Brazil as this is where most of my miles will be done. Because I have no time schedule I am free to change my mind and explore anything that takes my fancy.
It will be about 12 to 14 thousand miles, I will aim to do around 1000 miles each month.