Senior Member
United States
100% polyester is a plus?

I see no reason why a tailor wouldn't be able to alter swim trunks. Tailors can take in pants and shorts, so I don't see why swim trunks would pose a problem. Might cost a little more than shorts due to hand work as you mention, but it can almost certainly be done.

Best method is to ask your tailor of choice if he or she would be willing to do it on your next visit before purchasing.
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