If you get the 60 day visa exempt stamp and extend by a further 30 days at the Immigration office, Immigration class you as a tourist. If you then attempt to enter again on a visa exempt stamp, Immigration rightly consider that after on 90 day stay in the country that you are no longer a tourist but that you are attempting to live long term in the country. While there is no legal limit to the number of Visa exempt entries, once the Immigration officer believes that you are no longer visiting the country as a tourist he will deny you entry. If you have already stayed for 90 days on a visa exempt entry, then in future to guarantee entry into Thailand, you need to obtain a long term visa suitable to the reason for your stay.
You are contemplating Undertaking a process which is illegal and if found out by Innigration, you face possible imprisonment and certainly expulsion from the country and you query whether the process is normal. If you do not have sufficient funds to stay legally in the country go home.
To obtain an extension of stay based on marriage you need to have a Thai bank account. To open a bank account you need a long term visa (You cannt open a bank account on a tourist visa or visa exempt), Be aware that while an marriage extension requires 400,000 thb in your bank and a Retirment extension (for those over 50 years) needs 800,00 thb in the bank, that a retirement extension is much easier as it requires you to jump through ,amy less hoops.
If you get the 60 day visa exempt stamp and extend by a further 30 days at the Immigration office, Immigration class you as a tourist. If you then attempt to enter again on a visa exempt stamp, Immigration rightly consider that after on 90 day stay in the country that you are no longer a tourist but that you are attempting to live long term in the country. While there is no legal limit to the number of Visa exempt entries, once the Immigration officer believes that you are no longer visiting the country as a tourist he will deny you entry. If you have already stayed for 90 days on a visa exempt entry, then in future to guarantee entry into Thailand, you need to obtain a long term visa suitable to the reason for your stay.
Thai Immigration consider that one 60 day entry (plus a possible 30 day extention) on a visa exempt stamp is suitable for tourists. However Immigratin consider thyat if you attempt another 60 day visa exempt entry within a short period that you are no longer a tourist. After one 60 day visa exempt entry get a longer term (actual) visa for the reason of your stay in Thailand.
Are you over 50 years? If so obtain a Retirement Visa for 12 months in Australia. In Thailand, Two months before visa expires have 800,000 Thai Baht in a Thai bank account, then apply for annual extension of stay based on being over 50. I have been doing this for over 12 years. Very hard to get an initial Retirement Visa when in Thailand because Banks will only open an account for you if you have a long stay visa,