If you go on sabbatical to Thailand for 3 months and apply for a visa with all the details like flight booked, accommodation etc. Then you get an approved e visa type tourist TR with validity date (issue date so not the date of departure) and expiry date (3 months after issue date and thus shorter than the actual date of departure from Thailand. Is this correct then and if not; which visa should we apply for?
TLDR : Answer Summary
If you're planning a 3-month sabbatical in Thailand, as a citizen of the Netherlands, you may not need to apply for a tourist visa (TR) because you can enter Thailand using a free 60-day visa-exempt entry stamp. Moreover, you can extend your stay by an additional 30 days at an immigration office for a fee of 1900 baht.