I've been working offshore doing
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&
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in and out of Thailand on visa exempts since the end of 2010. In this time I've had two tourist visas only, the rest have been visa exempts, I also spent about 6 solid months here when I was laid off at the end of
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and I extended various visa exempt entries for 60 days as I have kids here. For the last 8 months I've had a non imm O.
All in all, I've been asked at immigration twice what I'm doing here and why I come so much. A quick explanation at the desk and in through to collect my baggage both times. I've never actually had to show proof of anything.
Based on my experience I think you'll be fine, but have the three proof of's too be sure. They're definitely clamping down.