I was divorced back in 2016 after 6 years married, I have 1 child aged 7.
On the day of the divorce, we just went along to the Umphur and took a ticket, no appointment needed, same office we got married. We were asked about finances, land house etc, all which I had no claim to anyway, then we were asked about child support, we agreed on 8k a month, that is now 6K, soon it will be 4k, then when I retire nothing, bearing in mind in Thai law, both parents are equally responsible for child support. The reason for the drop and that I'll pay nothing when I retire is that I built a rubber plantation on my sons family land, 2600 trees, this was so they could be self sufficient, and could support my son, I want no gain from the plantation, and they already make an income off it.
I visit my son every 3 months, visit his school, take him out of the village, the family are all good, and I do give them extra cash when I visit, buy all his school clothes etc, the grandparents look after him, ex is with new child and Thai husband and not at the house I built.
I'm not prepared to fund my ex's new family, hence no funds when I retire in 2 years, the plantation I financed was for my son.
5-10k is more than enough to take care of 1 child, don't forget whatever you pay, the mother should be paying the same, so don't let them say what you pay isn't enough.
PM me if you want more details on the divorce.