A little update after my overstay expreience:
I have been on an O visa for over 4 years but managed to overstay a visa exempt by 30 days. Hua hin immigration were great, at first they simply said,
pay now or pay later when you leave as we can not issues you with a 7 day extention as its past the date any visa could be issued untill. I mentined I had a son and the guy said
go get his birth cert., copies of other things and we will give you 60 days from your over stay day. 40 minutes later im all legal with anothe 30 days left, minus 17800bht.
But also no red stamp;) I would like to thank Tom and rob, for all the valid advice and say a big fuck you to thai visa :)