I put a lot of money into fittings and saddles trying to find one that would avoid my "numbness downstairs" issue.

I actually only resolved it when I was trying to fix a non-biking leg injury. I did this warmup/flexiblity program called Limber 11:
https://www.bodybuilding.com/fun/lim...ever-need.html

That was the first major step. I found out that by improving my bodies mobility and core strength that biking could be much, much, much more comfortable.