British Guyana
Britain had one colony in mainland South America. It was a bit of a backwater and in real history, operated by absentee slave owners. Its main exports were bauxite and gold. Just keep out the pesky Venezuelans (the. The Spanish got kicked out in 1811, so the only developed nation likely to come snooping is the USA, and even that is less likely than in Canada, plus bodies can be easily hidden in the jungle).