Looking for an "almost naked" type square cut speedo for 42" waist.

[PSDave]

I'd suggest getting one that comes as close as you can get to fitting and then take it to a tailor and have them make one for you. They can see the design and construction and alter the measurements to fit your body. (If there is a costume designer/maker available to you, they can makeup a suit from the picture at the Andrew Christian website)