Sounds more like you are hunting for a live-in-maid who also provides sex as service.Nothing wrong with this approach since many of our grandpa generation married similarly.Unfortunately time had changed and so has many third world countries including Thailand.
You are better off looking locally since your greatest disadvantage is that you are a foreigner and Thais who marries farang views them as a walking ATM......no kidding.
I am not suggesting that all Thai girlies are gold diggers but one must understand Thais are class cultured people.Farangs marries girls whom Thais do not want.Because almost 90% of those who marry a foreigner comes from the so called poverty stricken North East Isaan region .Actually they are more of Laotian than Thais.Thai men usually wants to marry a Thai girl who is 1 hierarchy above his class.And they are never married to ex whores and Thais can tell who whores and who do not whereas we as foreigners cannot.A good Thai society girl approach dating very subtly not directly.....usually through friends.
So may I suggest you seek a good Thai friend with a good standing in the society first.
Actually, there are many Issan who are rich. The main problem is many Issans especially the uneducated or lowly educated do not spend within their means and gambles even though many are land owners. Every year, I will stay in Issan for 2-3 months and my observations, the "proverty" came from a few things, gambling is top. buying too many things. Most farmers can easily earn minimum THB 100,000 per rice harvest for a plot of 20 rai land. After they get the money, they start the usual buying. Buy pickup, buy motorcylce, buy TV, buy aircon, etc. and buy almost everything with installments. The remainder, they gamble away. Then, they start to borrow money for the next harvest. And next, daughters/wifes have to move to cities to work as WL. The smarter ones are the ones that save the money. It is a big business in Issan just to provide financing to these farmers. Unfortunately, this business is only for Thais. Smarter Issan girls also do not want to marry Thai men as there are too many examples of abandoning family, not working to support family, drunk and gamble.
For Thai girls dating, you are right. Thai girls will be seen as loose if they are too fast and direct. Slow and steady.