I've been riding a long time with real weight on my hands. I'm skinny, light, long and with just a few slow twitch muscles. (No fast twitch at all.) Not a good upwind combo. I've also been riding fix gear forever; sometimes long rides. Only way to make all that work is to ride with a flat back. I accept that the most comfortable way to do that is with my arms slightly bent, the handlbars a long ways away and real weight on my hands.
To do this (I'm 69 yo, not a youngster) I choose handlebar shapes and brake levers that work for me and I pay real attention to the setup. On any new-to-me bike, I do my early rides with no bar tape, just the cables electrical taped to the bars. Wrenches for the stem, bars and levers go in my pocket (and a 6" crescent to assist with the brake lever clamp bolt). Bars don't get taped until I can both ride and fell good after. And still, they get taped with just cloth tape from the bottom so I can unwrap and rewrap any time I feel the levers need to move.
Oh, I look at the "ergo" (edit!) bars and cannot fathom how I'd get that wrist rotated forward riding them. My choice is bars looking like the TTT bars of the '70s where the tops take a steep angle forward and down when the drop flats are horizontal.
In the past several years, hand issues similar to yours have been showing. One summer I tried rotating the bars down, not back when I noticed the left lever was lower than the right and my left hand was fairing better. Both hands felt better. I continued rotating the bars down until no issues. They are now set like racing handlebars 70 years ago with lots of downward slide to the uppers behind the brakes. They don't work as well as parking places for my hands but no issues! During rides or after. I'm coming to believe (again, for me) that my hands rotated forward, thumbs up and forward, pinkie back works. That the popular brake levers high and pointing up is the worst thing I can do. All my other bikes now follow this first one and re-occurring hand issues are no longer an issue.
If you do as I do, you may need a further upward angled stem to offset the additional reach the rotated bars give you.
Last edited by 79pmooney; 09-27-22 at 06:15 PM.