Mexican taxes on distant working within the US

Customs duties on fully assembled units or imported used vehicles from Japan.

Hello again. I'm still trying to get an unequivocal answer as to whether U.S. citizens who are Mexico residents (normally, under Mexican tax law, a person who spends in Mexico more than 183 days a year is Mexico resident) is Mexico resident of Mexican income taxes need to pay non-Mexican income. This could be things like interest on US bank accounts or, in my case, freelance and other income from online work for US clients.

I scoured the internet for information and even posted the question on this forum where I got helpful answers. However, the problem is far from being solved. Some people are absolutely convinced that Mexico does not tax such income. Other people (and Mexican tax law as I read it) say it does.

If it were just a matter of a year, I would do what everyone else seems to be doing and just not care. For one, how would you know? But before I commit to spending years (and possibly the rest of my life) in Mexico, I need to have a final answer.

My question now is how can I get such an answer.

From my point of view, there is an opportunity for me to contact a lawyer or tax professional in Mexico (where I currently am) who has regular dealings with foreigners. If anyone has suggestions for such a person, I'd love to hear them. (I speak Spanish so language is not an issue.)

The second option would be to make an appointment with the Servicio de Administración Tributaria (SAT) and ask them directly. However, I'm not 100% sure how to do this without CURP.

Any thoughts on which route would be better? Any other ideas?

Many Thanks.