Many long distance cyclists ride with gently rounded backs with a bit higher handlebars. Here is Mark Beaumont on his around the world in 80 days record ride. Even on aero bars he has a comfortable, non-extreme position. Having handlebars at a height that allow you to keep your elbows bent when riding on the hoods is important. Saddle set-back and angle is also important to help find comfortable position. I found this blog post by the amazing frame builder David Kirk to be helpful.
Riding tip | Kirk Frameworks
