longer ride soreness

[1K9]

So, when I go for 4-8 hour rides on the rocket, I usually come home really stiff and sore, especially around the back, shoulders and neck. I just figured this would happen on any motorcycle.
Well, I rented a bmw r1200 gs adventure, while on vacation in colorado last week, and rode for about 8 hours on and off road. When I got home, my wife commented that I wasn't stiff and sore like I usually am after a ride. I didn't even realize it, until she said something!
Anyways, does anyone have any idea how to Take the sting out of the rocket?
Considering new rear shocks, and/or seat...

Take 2 naproxen or the like before the ride. Rub some oil of old age before the ride and drink it after the ride. My bike came with a throttle lock, risers and cruising seat. I added a gel pad to rise me up a little to see over the windshield. It feels comfy. We'll see how I do riding all the way to Leakey. Have not ridden that far in years.