Luang Prabang, is UNESCO world heritage site is the best place. Beautiful and wild very inexpensive. I am surprised no one mentioned this in comments. I guess they don’t travel much.
you can if you’re doing in small amounts you can have a few private clients. the same way if someone comes to my house and asks me to teach them chemistry or physics and they pay you some money to do that. no one cares what you do privately. as long as your not setting up a business