hi, breathless,
I shouldn't worry. I did the Singapore run for 8 years on a 90-Day visa. And the
JB guys are hassle-ready but that was on the way out. Coming in it was easy-peasy. Amazing what an honest face can do for you - plus the Tourist camera, Hawaiian shirt and Polaroid sunglasses.
I didn't have the hat with the corks but a jockey cap with "I Love Malaysia" on it always helped.

If you're doing Thailand, Langkawi, places south, Singapore, Sarawak, then Sabah, I'd reckon your passport will wear out years before immigration has a go. Sounds the perfect yottie/tourist run. Throw-in a couple of longer term haul outs with trips back home and that's it for 20 ++ years.
Some friends on mine on a yacht in Langkawi were there for 15 years or more on a tourist visa. Some trips up to Thailand on the boat, some runs to Satun on the ferry. All very legit so no problems.
