(iirc we've never heard of anyone Apparating across thousands of miles of ocean either, although it might be possible if they'd already been where they wanted to go and could picture it, and were exceptionally powerful)

I think the key is in GoF...we don't see foreign wizards and witches apparating to the QWC game, they required the use of a portkey. Ditto later in the book, neither Durmstrang nor Beauxbatons apparated to Hogsmeade, they arrived via PHYSICAL means, magikal tho it may have been.

So there seems to be a distance-limit on apparation. Altho it is in the realm of possibility that the inability to apparate great distances has more to do with crossing international borders than any magikal constraint. IOW, the thing that keeps wizards and witches from apparating to other countries is solely political, and not physical.

But just like nonmagikal people illegally cross borders, you'd have magikal folk who didn't care about breaking laws apparating to other countries -- so I still lean to there being a distance limitation to apparation.

Which leaves travel via portkey. But in colonial times it would have taken months to deliver a portkey, and it could only be used once.