not every provinces require that. Samut Prakan only wants a TM30 when you come from abroad and only that is required for 90 days report, or a Visa extension. You can go one week in Pattaya or Phuket or anywhere in Thailand without any needs to resubmit a TM30 when back to Samut Prakan
If you have at least 15 days left before exemption expires, you can file a TM87 to change your Visa status to Non O. Financial proof required tho (400k baht in a Thai bank)
yep. Or you may go apply for a Visa in Savannakhet or Saigon as a plan B. Price for non immigrant O multi entry and valid for 1 year is 5000 baht in Laos and USD200 in Vietnam