You don't have to have your funds seasoned for your in-country Non-O visa based on being married to a Thai, but you need to have a specific number of days remaining with your current stamp. Most offices require you to have 15 days, but some do 21 days.
If you meet the requirements, you can apply for an in-country Non-O anytime now.
Otherwise, your option will be
1. 30 days tourism extension
2. 60 days family extension (<- better not use up unnecessarily because this usually is one time deal per visa)
TM87 is supposed to be an application form for an in-county Non-immigrant visa for people who entered WITHOUT a visa. If you entered on SETV, the form has to be TM86. Check with your local immigration office.
Here is the general information for in-country Non-O based on spouse application. Get the latest and Nong Bua-specific handout.
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