Interesting. Reminds me of when I did gravel riding before there were gravel bikes.
I’ve found myself quite comfortable going down harshly washboarded roads on 32mm tires (GP5000). Strange, huh? I was trying to figure out the difference.
Fit is big. If you are standing, squat so your knees form 90 degree angles and put your hands out front of you. Comfortable? This is the position I’m in on my bike. Notice – there is no weight on my hands. I have a bike where my reach is too long, forcing me to put weight on my hands, and that bike beats me up on gravel. With a shorter reach, there is little to no weight on my hands. I have a very stiff fork, but I don’t get much vibration because there is little weight on my arms (and my grip is loose).
Certainly a redshift stem is great, but if I am not overloading your arms I don’t really need one.
For the rear, I got lucky and my bike came with the worlds best carbon seat post (much to my surprise and delight). Its just magical soaking up washboard and stuff. Alternatively a small thud buster works great, and is adjustable for weight – that might be a good call for you.
It looks like you got the tire pressure right for the tire size and your weight.