What are my options for extending my Non-O visa while I am out of Thailand?

Hello

My extension of stay (one year) based on marriage (Non-O)

expire middle of October

Normally I do apply for the next extension 4 weeks before...

Now my situation is that I will be out of country at this time until November.

What would be my best option (I not resident at my workplace)

Can I enter Thailand, get a 4 weeks waiver and do a new Non-O here in Thailand and a new extension?

Or

How short before extension expires I can still do the application for extension?

Or

Can I do the extension now (with a still valid extension until middle of October)?

Maybe only for a few months?

Or

Is it in Singapore possible to get a new Non-O (not resident there)?

Thanks for advice.