Tires are 90% of what is being called compliance. Or comfort. Unless you are truly a featherweight 50psi in a 30mm tire should take care of it. If it doesn't, you have a lot more analysis to do.
Most mass market products are made to survive Clydes. They have to be made stout or they get absolutely trashed in fora like this one. And then there is the fear of litigation.
If the problem is the frame then replace the frame. You could try twenty saddles and ten springy seatposts and not get there. Sounds to me like what you want is not a mass market frame and not a niche frame. You want a custom. That or explore antique frames from when racers did weigh 120 and 140 pounds.