jump to conclusions much? I've spent 10 years in Thailand and seen shit the OP would never dream would happen. The fact that he's already supporting 2 families in the village and ready to invest in a business for them is sign enough that he's fucked. Getting married will only amplify his problems. Setting the standard for the village that you're their bank is a recipe for disaster. This will not end well. Trust me.
I've been visiting Thailand regularly for the last 9 years and I've never once been asked for anything other than my passport at the immigration counter. You'll be fine.
Hi David, I'm interested in selling this type of experience. I have a new tour agency selling tours across Thailand called Tour Explore Thailand. The concept is to tour traditionally and explore locally. Our main areas to start selling are Bangkok and Samui. Feel free to send me an email with some of your ideas for experiences along with what you might charge. Look forward to hearing from you.