What are the options for extending a 45-day visa exemption in Thailand for a Belgian digital nomad?

WOW, don't admit you are working, no options for Digital Nomads.

It seems some experts never did read any of the Immigration Visa rules.

The Non Immigrant B visa allows everybody to work inside Thailand in combination with a Work Permit, the ideal combination, You can tell every body you work, you contribute into Thailand with paying tax and you have social security,

And the biggest benefit, you do not have to leave Thailand as long as you work, as each and every year you can apply for 1 year Extension of Stay based on working in Thailand at your local Immigration Office.

Live can be so easy and legal if you just pay a little attention to the rules.

BUT whatever option you choose, strictly speaking you are not allowed to work, not even remotely, on a visa exemption or tourist visa

Don't admit you are working !

As for staying longer ..

You should have applied for the METV multiple entry tourist visa before you left your home country. It would have given you up to 9 months to stay in Thailand.

NOW you are needing to do border bounce to get new visa exempt entry 45 days plus one 30 day extension of stay.

Border Bounce can be done 2 times EACH CALENDAR YEAR.

A 30 day extension of stay is available at your local Thai immigration office for 1,900 Thai baht. These are the common found requirements ...

You can extend once for 1900baht (30days) then you will have to leave Thailand and return. There aren't really any good options for Digital Nomads.

How about stating WHERE you stay in thailand so people can tell you what office to go to.

you can get ONE 30 day extension on your 45 day visa exempt entry stamp for 1900baht a the immigration office where you stay.