You also can extend your visa after the 30 days and all they are interested is the money you pay for the 30 day extinction. No documents asked either. I got it done at ITSquare. Laksi. If you have your ticket out of Thailand even if it is more than 30 days after your first arrival it won't be an issue.
The Immigration now only asks for your boarding pass and nothing else unless they changed it this year? 2024. I do not think so. It is the airline that will ask for the ticket and since you have one then it is not an issue.