I give you this advice: the regular sites are okay to find a ‘normal’ working Thai girl. But do one thing and stick to it: make a good quality profile about yourself and what/who you are looking for. Then neglect all responses that are obviously from women who didn’t read your profile, who clearly are not interested in you as a person or not qualify with your demands. From the few that are okay, pick one by one (be respectful!) and make video contact with her. Use the Line app.
I did this myself. Used the ThaiFriendly app. Now, after 2,5 years, I am married with a Thai woman from a good family and with a good job.
Forget about all the guys above who just have prejudices about Thai women. Of course there are many examples about the practices of golddiggers. But these examples don’t make a whole truth!
Zo’n verklaring is natuurlijk handig, maar niet strikt noodzakelijk zolang er ook voldoende bewijs is (kinderen, zorgplicht familie enz) van andere redenen om na de visumperiode terug naar TH te gaan. Misschien kun je op een andere manier aangeven dat en waar ze werkzaam is. En als je zelf de garantsteller bent voor het verblijf in NL, kan het meevallen. Succes!