I’m not sure what the OP has done unless I missed it when reading through.
Anyway, I’ve never had any luck with a stock seat except on a Goldwing and Ultra Classic.
I’ve used corbin, mustang and ultimate.
Although the corbin and mustang were both much better than the stock seat, I still got numb bum pretty bad.
With the Ultimate low rider without backrest I can literally do 9 hour days in comfort. For me it’s the best seat I’ve ever ridden on.
I’m only 5’8” so the low rider works for me but I have a friend who is 6’ and about 300 lbs. He said my lowrider made him feel like his balls were up on the gas tank.
Anyway, my votes for the Ultimate seat.