PC: Peru Without Panama

How reasonable would it be for some European power to take and hold Peru with a supply chain passing, not through the Caribbean, but through the Río Plate region?
There was trade between Peru, Upper Peru and the River Plate. However, if contested by the power holding Panama, I doubt the Peruvian colony would be able to hold, at least in the coastal regions.

Even today, a road trip from Buenos Aires to Lima takes about 40 hours, and that's in buses going at 80-100 km/h through asphalt routes, with lots of towns and gas stations along the way. Now consider the same journey on horseback, or carriages, with no routes to speak of, few if any bridges, some scattered inns and the sheer inhospitability of part of the journey.

And the route south, through the Magallanes Strait is dangerous as well. It can be done, but it would be too difficult.