You need to report your residence. Your Landlord should do it but sometimes it is easier to do it yourself. At my office I required lease agreement, house book of landlord, house book of rented property, copy of landlord ID card signed, copy of passport. TM 30 form completed and signed by landlord. Tgen they also needed to speak to my landlord while I was in the office. No idea what was said. Got my proof of notification to keep in passport.
I want to buy a car but as you say it is idiotic. Nakhon Phanom IO certainly dont regard it as irrelevant. They will not give me a residence certificate. I was told to leave. Can there be a more uncooperative IO?
I have done my TM 30 in Nakhon Phanom but local IO refuse to give me a residence certificate because my Visa came from Bangkok. So if you move home you are stuffed until your next Visa extension.
Presumably you dont have a current Visa but a previous 45 day Visa exempt. Why not extend locally 30 days then do border run as planned or have you done that already? I did this several times at the Mukdahan border crossing no problems but only twice in one year.