2) I promise you it's perfectly normal for people living in Thailand and employed in Singapore / HK (and I am sure other places) to travel to their office or other locations 20 times a year (I am one of them). They would just need a work visa / pr or citizenship in the country their firm is in. Yes the Thai stamps in your passport get annoying and yes it is exhausting but hey ho.
3) The OP's reasons for travelling 20 times a year are totally clear. He is going to Indo to see his family.
why would a remote worker not need to travel regularly? You work in Thailand day to day, travel to Singapore or HK for meetings or to visit your office. That's the pattern of half the remote workers in Thailand.
Yes, appreciate only one parent needs to be Thai but from memory friends who applied for Thai citizenship as an adult had to have both parents physically in the country as part of their application process, even if one was not Thai.
a lot of Thai people who were born overseas never get their Thai citizenship in order. I understand it's fairly straight forward to get but you need to have both parents in the country, there may be an obligation to enter for national service etc.
Although I have now got two opinions from Immigration (albeit different ones) and your opinion, I am still inclined to go for a fourth check and pop by BlueTree Immigration tomorrow. Good advice and agree it can only improve my chances of success.