Originally Posted by Carbonfiberboy

Every saddle has a slightly different sweet spot for my butt, meaning how far back on that particular saddle do I find myself sitting? I get my fore-and-aft position by the balance method: can I lift my hands off the bars briefly without sliding forward on the saddle? I.e., I don't measure unless I'm using the same saddle on more than one bike.

I find I am more comfortable on long rides if I'm more stretched out than you are. When riding with horizontal forearms, I like my elbows to be just ahead of my knees. For my body geometry, that happens to be when my upper arms make a right angle with my torso, so quite a bit more reach than you have. You might experiment with considerably longer stems than you have now, see how that works for you. I feel most comfortable with a 30mm setback post (Velo Orange) and my Selle Italia saddle almost all the way back on the rails. I use a road bike bar with drops and brifters, which might make a difference. I like the varied hand positions which it provides. I spend a lot of time with the load on the side of my hands rather than my grip. Geezers tend to do relatively better on long rides.
https://velo-orange.com/collections/seatposts

My bike fit primer is here: https://www.bikeforums.net/21296948-post3.html