I’d go with a proper hard case, as I’ve just had a nightmare lugging my road bike from the UK to kansas in a soft bike bag, grnated most of the nightmare was getting the bike to heathrow, but that’s another story.
Also, Northern Thailand is pretty cool for riding, back when I had a Thai girlfriend I used to use the visiting family ‘holidays’ to get some riding in up in chiang mai, there’s nothing quite like hammering through coffee/lychee plantations.
I’d recommend x-bikers chaing mai if you’re looking for guided DH type riding, and they still exist (it was a few years ago now)