yes, that's absolutely right. I just wanted to share my experience with you in case you find yourself in the same situation. I presented all the required documentation, yet they turn me back. It was in Hanoi, they also gave me my money back which makes no sense if your visa is not accepted. The processing fees should be paid anyway.
Omg, in my experience thai embassy in Vietnam is really tough. Last time I went there they had a pile of photocopies they were giving to each of use after 1 day waiting saying they weren't able to handle a tourist visa for us for some of the 3 reasons you could find on that paper. Good luck with it.
As far as I know, vaccination rules depend on the province you are flying to. So, there's not a single criterium for the whole country but each province applying its own criteria. In the specific case of Bangkok, you are not required to show anything to fly in. Of course, to this, you should be aware of what some people have already said in the comments, enforcement of rules in Thailand is very poor, therefore most of the times it is up to the company or airline to ask you for it.
I haven't done this exact route but I have cycled most of Thailand on my bicycle alone. Just quick tips, carry enough water, some snacks and I would suggest to keep some fried or grilled chicken with sticky rice in your panniers. This is Thailand so most of the times you'll find a little shop selling noodles. Be ready to eat a lot of noddles.
If you are planning to camp, reservoirs and temples usually allow you to spend the night without problem though you might be rejected sometimes especially because of covid related fears.
Choose coastal roads or secondary roads rather than the main road which is by far the most dangerous you could do.
In any case, dm me if you need any more help or you have any other questions!
I got a similar one from my hotel and it was accepted without problems. In any case check if your hotel is listed as an SHA+ hotel in the government list.
