. . . the immigration officer actually tried to be helpful when he told you to visit on he day your Tourist Visa extensions runs out. The reason might be that if he issued the extension today, he would have needed to start the 60 days from today. He lets you apply for it on March 4th, so the 60 days will start on the March 4th. Thus he actually wants to ensure you receive the full amount of the 60 days Covid19 extension and don't lose any days until march 4th
You have not extended a „visa“ by 30 days, this is wrong wording . . . .you have extended the „admitted stay permit“. An “admitted stay” from a 60 days Tourist Visa can only receive a 30 day extension once
What you could do, visit Immigration and ask them if they are willing to give you the “60 days unable to fly due to Covid19” extension, before this special extension for people “stuck” in Thailand runs out on March 30th.
However be aware if they grant you these 60 days, they will count them from the date you apply for
or apply for the 90-days Non-Imm-O based on marriage on an embassy or consulate in the USA. Finances can be either in a Thai bank or a US Bank on the date of application. Then after 15 nights quarantine, open a bank account and transfer the required 400K THB. They need to have seasoned for 2 months on the date of the application for the "1-year extension of stay permit based on marriage"
or fly back to the States, apply for the 60 days Tourist visa at the embassy or general consulate in the USA, and the COE fulfilling all the requirements. In Thailand, before the 30 days extension of the60 days tourist visa runs out, apply for the 60 days "visit family" extension, This would give you 60 plus 30 plus 60 days for transferring 400,000 THB into a newly opened bank account in your sole name, and let it settle long enough. Then converse the "visit family" to a 90 days Non-Imm-O based on marriage to a Thai at the Immigration inside Thailand, and from there change to the "1-year extension of stay permit based on marriage with a Thai"
if Si Racha immigration is not helpful, it would be worth checking if Jomtien Immigration would give you a Covid19 extension any day before March 30 (or before your 30 days TR extensions runs out). But be aware you must use the Immigration which serves your area of residence. In order to use the Jomtien or any other office, you will have to change your residence adress, TM30 and all
I'd say, if that receipt stapled in your passport that says "have to report for 90-days on (date)" says you should report soon, then you can do this on just ANY immigration office in the country. However you COULD be asked where you currently stay, if it is not a hotel which would otherwise have registered your TM30, but a private address, you MIGHT be asked to fill a correct TM30 (which actually has nothing to do with the 90-days reporting)
90-days Non-O married to Thai, then after entry in Thailand, park the 400,000 THB and before the 90 days run out, apply for the 1-year extension based on marriage with a Thai . .with this extension he can leave and re-enter Thailand as he wishes, he only needs to buy a re-entry permit for each trip