They are getting tougher on those who break the rules now and you have put yourself into that category and will come under a lot of scrutiny. Really bad idea.
No agent needed at all. Tourist visa will.be fine as.long as she has money in bank and a job or business to return to. They are looking for proof she will.return home and that she will not be working. Basically they will approve professonal working people but not bar girls.
Lots of people will try to convince you to.try to circumvent thai property law in this way. But it is illegal. The business must be legitimate and have reason to hold the land. Just the way it is here.