If you can get a Non-O in Germany and possible Multiple entry, get it. Fort single entry, you have to extend it to stay in Thailand for more than three month. For multiple entry no need to extend. Just leave the country every three months and enter. Extend it inside Thailand for one year only for single entry. If you don't want to keep 800K in a Thai bank, you can hire an agent (in Pattaya for 15K) who can extend the Non-O for 15K without money in the bank. So, it will be 15K every year and no need for 800K in a Thai bank. That option helps lots of people who are not fortunate enough to be born in a Western Country to earn dollars and it helps you also by giving you permission to stay in Thailand without any required money in the bank or paper hasle at the immigration.