I have been fortunate with the back-door visa (Volunteer), but I don't recommend back-door services. I would recommend doing legit always. Even if that means doing several visa runs a year. Penang is a nice place to visit, easy to get a visa, why not go there. It maybe inconvenient but so is detention. "Up to you" as they say.
Thailand is cool that way. I was recently passing through US border control. They're kinda dicks, US Passport holder here. Y'all can tell President Biden I said so.
Pre-covid you would see people in this group getting denied entry at both land and air immigration checkpoints. Both were rare (in the group, in life I have no idea). If you cross at land border you can go back and find a new land border and try again.
If you're rejected flying you could be sent back you your home country, a country of your choice, or back to the country you came from (I think). I believe you have some influence but not all. When I was doing risky border runs I would cross by land. Another option maybe is to use a smaller airport. I had a volunteer visa. A lot of people were having issues getting through BKK, with volunteer visas. I flew into Phuket no problems. From what I understand Phuket is known to be friendly.
I did tourist visas for few years. Twice I was questioned when coming back. Both times the immigration officer would say 'next time you come back', they knew I was doing a long term stay one tourist visa at a time. One of those officers suggested to me, its best to stay away for a couple weeks at a time, maybe get married, avoid ED visa (because of my age 40+). After that I would travel a few weeks get a new tourist visa, return..
Australia was providing Multiple Entry Tourist Visa to US citizens, maybe others. So I would go to Australia a couple of weeks, pull a METV, return, do border bounces every 90 days (9 months), then repeat.
Post Covid, I am not sure if Australia is still providing METVs or if they are even available anywhere.
What you are doing is risky. Not too risky but there is a risk. Highly recommend you have a plan B.
Make some Thai friends with some influence. I had a friend that clerked for a judge and her father was a police man. She never got me out of trouble with immigration but she did make things easier whenever I had legal issues. I would always tell her when I planned to come back into Thailand so she would wait for my call, if I got in trouble or not.
Eventually I did the wife thing. So far its been ok. If you want to know more about that PM me.
Please read the the OP carefully. The OP does not mention any thing about 600/day. If you would like to know where in Phuket you can stay for 600/baht a day, please post a new question and not hijack the Original Post.
I vote Penang. Cambodia and Lao in my experience would be boring for kids. Penang, is beautiful country, you can rent a motorcycle, plenty of activities.