i believe it is also possible that he don't spawn at all. i would at least get two things verified before spending 24 hours sailing around. is he spawned at all and is he on the outer rim.

on my map i was about to give up and check the website, but then i realized there was a small chunk i hadn't explored. of course, there he was, the last place i look.

what im trying to say is. if you feel you have done a just search, and actually way above effort to find him. id say that makes you eligible to check the map. exploring way beyond where you are supposed to is also spoilers in its own way imo.

if im not mistaken you can set the map generator so that only haldor will show, unsure if you can tell it not to reveal map. thats a minimum of spoilers.