I have a multi entry Non-O and I have to leave every 90 days. Not a problem as work takes me outside of Thailand... But I don't need to hand over any extra money when I re-enter... Will never be using Ranong... lol
been in Thailand 20 years. Never been asked to show evidence of my passport or work permit... only shown my driver's licence a few times at police checks. Never had a problem with that either
Seeing u r a pom Pa, if u & your wife are legally; it's much easier to get your wife a visa to visit your country... I'm Australian and been married for 31 years, my wife has never been rejected for visiting down under & also USA...
As long as your paperwork is correct and truthful, you wife will never have a problem unless the finance side is low in funds to support her, depending on how long her visits are going to be...