I agree completely with you and if Obviously sold a swim trunk I'd certainly be a purchaser. I've been getting a lot of emails from Chubbies so you might have a look at their product line. The customer reviews are very good.
Personally I wear a swimming jock strap. Yes, they make them specifically for swimming. You can't beat the support and it's much better than the terrible mesh liners. I can't believe that's what they're still offering after all of these years and I cut them out the instant I get them home.
I just came from a trip to Florida and was able to go to the nude beach. It was just wonderful and nothing untoward happened. In fact if was primarily heterosexuals and families with younger kids; none of which bothered me. It's so freeing to walk the beach in nothing and felt so natural; I loved every minute of it. Of course most of the time we were on a standard beach where trunks were required.
For our trip to Hawaii a few years ago I purchased some "Tan Through" trunks. I discovered that they were too thin for me to wear them without showing off more than I wanted. They sell coordinating bikini style swim trunks to I went back to the site and bought the same design but in the bikini style. Wearing both probably defeats the tan through purpose but that's what I wore sometimes on the regular beaches. The bikini gave me the support I needed and made the suit G-Rated. On the days we used the boogie boards I wore traditional style Polo brand trunks along with the jock strap as they were a bit more "rugged" for that much activity.
Hope this helps, sorry to be so long-winded.