That sucks bro. I empathize with your situation. Seems a bizarre design decision that every other death in the game leaves your inventory retrievable except for falling off the edge of the map.
I think the idea of this game being based on a flat planet is pretty cool and unique, but they should rework it somehow so that your items are at least retrievable if you decide to make that journey.
Feels too punishing for what is otherwise a pretty fun and surprising death... especially considering the effort undertaken to explore to that extent.