Just finished reading the entire thread. Love your adventure, all of it. Thanks for being so open about your life. You're a gifted writer
and I have no doubt that you could travel the world and make a living by writing about it. You need a paypal account!
I and others here want to buy you some GAS so that we can continue to read about your unique adventure!
Notes about the dynamic vibration which caused your high speed off: It looks to me like the custom designed Panniers are mounted to far aft. Their CofG (Center of Gravity) needs to be forward of the rear axle by several percent, more is better in this case. For your kind of adventure try soft and smaller as this would help too, these are the latest tech ones: http://www.adventure-spec.com/defaul...-panniers.html
You've moved the overall CofG of the bike to far aft and thus it's to close to or aft the Neutral point. This will cause instability to develop at a new speed (when compared to the previous configuration) in this case lower.
The rounded corner shape of the custom Panniers may be dangerous and thus cause an Asymmetric lift distribution in a cross wind gust such as when passing at speed and thus excite the dynamics of the total system.
If you don't remodel, then be sure to load all of the heavy item to the front and don't exceed a tested limit.
Good luck, stay rested and safe.