Originally posted by Zathabar:

No need to Mod. goto https://valheim-map.world/ and feed in your seed. It will reveal the traders possible locations he only spawns whene you visit the first one however. You can leave the map shouded in mist if you want to so you don't see too much thats up to you.

this. with how terrible the randomness in this game can be, you shouldn't feel bad at all looking it up. if thats not for you then just keep looking