Yesterday I rode a 200k brevet. 212.48km, 2.947m of elevation. Rode it in 9:57:10. My bike is a MTB, with 2.2 29 tires with 40 psi and unlocked suspension (works the best for me, but I rode lots of brevets on road bikes).
Seeing the description of your effort and equipment selection leads me to believe you are sucker for punishment. I like the part about the 40psi tire pressure and unlocked suspension the best.
Have you considered a tractor seat? Something like "big yellow" -- it comes on a John Deere 4000?
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