So you’ve tried many saddles, and can’t ride any of them even a third of the distance you want to ride without pain.Perhaps you should just give in and use the equipment that is designed for your issue: bike shorts/ bibs.

if it’s an appearance issue riding bike shorts while trekking, there are bike shorts often used for mountain biking that have the look of regular shorts, made of a padded under short, and a regular short on top. You can also buy padded liners designed for biking to be worn under regular shorts or pants.

Given that you can’t comfortably ride without padded shorts, and don’t want to ride with regular bike shorts, I’d try one of those approaches