I've lived in Thailand (in and out) since 2002 and have been doing Tourist Visa extension for over dozen of times. I know that Non-O visa, TM30 and confirmation from landlord is required for every extension. But i was never asked anything of sort regarding 30-Day Tourist Visa or Visa Exemption, i simply showed up at CW, took queue number, filled out necessary form, did a bit of photocopies for pasport front page and stamp page, wait until my number popup, submit every required docs, and pay up 1900 for an extra 2 weeks of stay. I'm not sure if Visa Exemption is allowed 30 days extension as i never tried it myself.
For Non-O visa, now that will need resort/homeowner/landlord as guarantor or so i believed.