Legally, a TM30 must be filed by the owner or landlord when an "alien" is staying at their property. Most tourists who are out within 30 days will not need a TM30 (By law it's still a requirement but simply won't be needed). TM30s are requested by most immigration offices when you go to do other business there. Immigration at airports never bother about TM30s. If your wife is your "landlord" simply get her to register the online service. It's very easy after that.
I don't know about your country, but in Australia I have a few properties which I rent out and provide me with a nice income. I would never sell to buy a house in Thailand which I would never own. That's pure stupidy