Originally posted by John:

RNG, i once had a map with all possible Trader locations to be near the edge of the world, hugging ashlands and deep north, i threw that map away cause screw that.

That happened to me in my very first run. I spent so much time trying to find him that at some point I read out his location from the game files. That was before the world generation website existed. That's why I have suggested that the trader should maybe be hinted at or get his own vegisivir, as a safety net against really bad rng.