@benja_smith When you want to ask a new question, you should start a new thread.
True-turn-up-and-pay-visa-on-arrival for Vietnam. Never heard of that working anywhere, nor any news or any plan or suggestion or rumour that such a thing in on the horizon.
A pre-approved letter isn't going to work at the Ha Tien crossing either.
If you want to cross at Ha Tien, you need to get a visa (NOT a letter) or E-Visa.
You can ask a travel agent in PP to get your visa for you. Or get an E-Visa here https://evisa.xuatnhapcanh.gov.vn
