@Chris ****
Brandon is right.
You cannot stay in Thailand on a tourist visa or on a visa-exempt any longer than 180 days within a 365 days period.
An Immigration officer has the right to deny entry if he/she thinks that you are misusing the visa-exempt entry as a means for a longstay in Thailand.
They will, at some point after they see the many entries and extension stamps in your passport, tell you that you are supposed to "get the right visa for your purpose of stay".
At this moment, you are standing in front of the officer as a wannabe "tourist", NOT as the father of a half Thai child, because you are NOT entering Thailand on the purpose of being a legal father to a half Thai child. Brandon wasn’t judging you – he just explained correctly how the Immigration officer sees you. You being not married to a mother of your half Thai son, “doesn’t cut any ice”, as we use to say. It doesn’t count!
You must get the right visa that fits your purpose of stay. There is a visa based on being a father to a half Thai child. Why don’t you apply for it before you travel?
WHY do you not apply for it on the E-visa system of the Royal Thai Embassy in Paris? This visa category would be a "90-days Non-Imm-O Visa based on supporting a half Thai child". With this visa, you can get a "1-year stay permit" for Thailand. You earn more than the required 40,000 THB you need to be able to apply for this visa.
So, GET OFF YOUR LAZY BUTT and check out your visa-options, instead of trying to enter without a visa and risking to get denied entry because Immigration sees it as “you have been in Thailand without a visa too long”