What is the point to have a 5 years visa if you looking to renew every 180 days, when you simple can go outside the country and come back with another 180 days every time?
You cant sell anything to Thai companies. Because if your contacts leading to an invoice in future, you are working and then affecting the Thai economy, which is illegal with dtv. So you cannot represent an company that is abroad and want to get in contact with Thai companies.