You could just go to a Water Park where Speedos are normal and worn by everyone like this one in Normandy, France.
http://www.saint-lo.fr/Sports-et-loi...ntre-aquatique
Download the flyer Aquatic Centre (pdf - 1.19 MB) too.
I actually went camping here:
http://www.camping-auxpommiers.com/
and used the speedos/squarecuts only pool.