The basics ...
The consensus in Patagonia is that forced-air diesel heaters are too fussy and will let you down. Simple diesel heaters are far more reliable. Our Sigmar got a year of nearly continuous use and didn’t fail us. We also installed a heater off of the engine cooling circuit, which was invaluable for turning waste heat from the motor into a cozy interior.
Reliable access to weather forecasts is invaluable. Our friends using Winlink reported that it doesn’t work in the canals, and our Iridium satphone was unreliable in Tierra del Fuego. Sailmail has a Chilean station that provides excellent coverage throughout Patagonia. The long-running Patagonia cruisers net is a great way to keep in touch with other sailors on the move.
Finally, learn some Spanish before you go; that’s the only language spoken by most Chileans in the south.