Clarion,
Sorry to ask, what is your Ferry range? I realy do not know for the 182.
I do a lot of Ferry flights up and down. From Guyana, I'd recomend Belem as AOE, there is a good imigration there, the we can work your way down in Brazil.
If you want sight seeing, go via seashore because it is beautiful, but will increase your Trip in at Least one day. I'd say it Worths!
If you wanna make it faster you may fly Belem, Palmas, Belo Horizonte, Sao Jose dos Campos (easy transit close to Sao Paulo), Florianopolis, Porto Alegre, Montevideo (Carrasco) and Aeroparque... Just a guess, i am thinking in a 800NM range or so. If it is less, we can work it out.
Remember, this is a suggestion and you are the solo responsable for your Planning. (no liability for ME here, ok?)
All the best,
Sydy