And you've tried saddles with various width cut outs? Too wide can be as bad as too narrow for some. Experimented with saddle tilt?
The bones that you sit on are not just two knobs a set distance apart. There are several structures involved, but think of them as rocking chair runners only turned around backwards. Their spacing gets narrower as you roll your pelvis forward. So you want your saddle to sort of match that between your very aero position and your less than aero position.
My son put his Trek Marlin on the trainer earlier this year. I rode it for thirty minutes and when I got off I too had a very numb perineal area that I've never ever had before. Looking at the saddle it was almost like mine, but way less cutout and the nose profile actually bumped up ever so slightly.
I've ridden many a long mile with out bike shorts and even some 100 mile rides with no chamois. So it's doable. But I don't any more. Though my chamois pad is thin compared to many others. If you don't like the MAMIL look, then you can wear bike shorts with chamois underneath some other shorts. But Pearl Izumi and others make loose fitting shorts with chamois too.
Did you say whether or not a doctor ruled out any oddball things about your perineal area?