To me the setback of the saddle is the distance from the sitbones contact to a plumb line through the BB axis. For me the sitbones are usually at the widest point of the saddle, and that is about8 cm from the rear of the saddle. Imprecise I know, but it’s often correct for me and I usually have to fine-tune some aspect anyway.

The big variation among saddles, aside from width and the height of the seating surface, is the position of the front of the rail relative to the widest point. This position limits the setback you can achieve with a given seat post.

If you need more setback or need to get your saddle rail away from the edge of the seat rail clamp (it’s stronger that way), you might want to look for a Nitto S84 seatpost, which has another 15 mm or so of setback. It’s useful for putting a B17 or Professional on a BB modern road frame with a 74 degree seat tube angle, rather than the more traditional 71 to 73 degree seatpost angles.

Saddle position looks good to me. Try straightening your upper back

[MENTION=551118]jadmt[/MENTION], My guess is that you are not in any trouble with riding position, with three possible exceptions, strictly from my personal point of view.

1. I'm impressed by the rear view, where I see you are a much better roller rider than I am. Also notable and impressive is that you have very little hip rock. I tend to edge my saddles up until hip rock becomes uncomfortable (let me count the ways ... !). Then I back it down a little, fine-tuning as the season goes on.

2. I wonder if your center of gravity is a little too far forward. If you are fully acclimated to that position with respect to hand pressure while indoors, great. But I find I move around on the bike a lot more outdoors than on the trainer. I lift my hands up off the bars for bumps, as well my butt off the saddle. That's a lot easier when my center of gravity is over the BB axis. But your saddle cannot be setback farther, without a deeper setback seat post. The post you have looks like a good quality piece. For more setback I would suggest a Nitto S-84, but its only available in 27.2 mm, and it's pricy. I don't think it's the only high-setback post, but it has two bolts to enable fine adjustment.

3. I agree with the comments about the Brooks rails. Yes, they are quite tough, and yes, they have been known to break. It's not necessarily due to sheer weight, but due to localized overstress over a long time, metal fatigue. I haven't broken one, nor an Ideale, Selle AnAtomica, or a Specialized, but I am only 5'6" and I'm likely to weigh less than you. Selle AnAtomica at some time changed its steel rail material to CrMo from, well, whatever it was.

With all these, YMMV, but if it was me, I would try increasing the setback, especially since it reduces localized stress in the Brooksie's rails.

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

I'm the same way. My attitude is, my body wants to be in a certain place due to leverage in pedaling, my skeletal dimensions, my pedaling, et cetera, et cetera. My body tends to be where it likes to move best, and it is up to me to place the saddle and everything else where it supports my body in the best possible way. It other words my saddle setback will not move me backwards. Rather it will make it more or less comfortable when I ride in my natural setback position. It's up to me, my choice of components, and my orientation of components to find comfort while pedaling in my body's most effective position. At the same time, I'm responsible for the actual durability of components such as saddle rails.

Actually, Carb, I tend to carry hand pressure mainly on the sides as well! I guess it's because it helps me keep finger contact with the brake lever.