EU expat China ,Slovenia passport . In Thailand for inspection ship of German Owners. What Visa need

I am an EU expat in China of Slovenian nationality. German Shipowners asked me to inspect their ship in Ko-Si-Chang , Thailand. Max length of stay 5 days. The owners/managers have own local shipping agents. Please suggest what kind of Visa I should apply for. Am I elligible to VoA when entering Thailand at Bangkok airport?