Strongly advise not to get any overstays, even if it means rebooking a flight. The rules can change. I had a 1 day overstay and had a v. hard time getting thru immigration about a year ago, and the overstay was a factor. Also, 2 overstays makes someone ineligible (as of a year ago) for the Elite Visa which is a great option if you have some money and want to live for an extended period in Thailand without constant visa and immigration worries.
It looks like a large figure but spread over 5 years it's not that much and you treated like a VIP, escorted thru immigration, free limos to and from the airport, first class lounge access, bank acco7nt and so on. If you are a regular visitor it's worth it.