Your English is just fine (way better than my French! )
You've made your choices ... that is good! Bon voyage!

Be careful of your back ... use proper lifting technique. (back into the bike, use your legs) Lots of videos on this, won't work in mud.

"Trends" in ADV travel show the bikes travelers use and the shifts in the way they travel are slowly changing. Over past 10 years we see a sharp turn away from big & heavy bikes, more interest in smaller bikes.

No one is saying sell off your Africa Twin (fantastic bike!) and buy a 250 Honda .. but "trends" show more riders are going smaller and lighter. Many former R1200GS, KTM 990, Vstrom, Africa Twin riders have traded in their big bikes for a smaller, lighter option.

Packing
Packing light is sort of an art form. IMO, requires several long trips for new travelers to learn this ... and learn what's truly needed (for them) and what can be left behind.

If you take a close look at what backpackers and bicyclists pack, you can get a few tips on light weight packing. Sure, motorbikes have more room and can easily carry the weight, but in rough conditions weight and bulk can create challenges.

The other thing no one has mentioned is that in some places you will not be able to camp ... or if you do Wild Camp, it may not be safe or may be crowded with people. This is true now for much of the world. When camped solo, you sort of become a prisoner of your camp. You can't leave it.

But soon all these realities will face you ... I hope you wake up happy everyday! (some days it is a challenge to smile!) Bon chance!

Hello Jean-Baptiste, sounds like a grand trip!
When packing for my trips. Heaviest stuff (pots, pans, kettle, tools, boots (if necessary) in a 49L dry-bag right behind me on the seat; I figure it's the same as having a small passenger.
Right hand, smaller, pannier for thermos of coffee, photographic equipment that is not in a tank bag, Katadyn Vario water purifier, dehydrated and freeze-dried food.
Left hand, larger pannier for medical kit and a small cooler-bag that holds six 20oz bottles of ice (I like COLD water). With the Katadyn filter I can get water from any source anywhere. I will also load up the rest of the left pannier with more food and munchies, almond M&Ms, chips, crackers, Clif Bars, Kates Bars, Quaker Oatmeal To Go squares (apple cinnamon is delicious!) I travel with a LOT of snacks.
Two 35L dry-bags packed with clothes, toilet kit, sleeping bag, pad, tent, tarp and generally everything else not previously mentioned, one on top of each pannier using ROK straps.
As for tires, when necessary to take them, which is fairly often, I strap them to the front upper crashbars using ROK straps.
I don't know if my input helps any, but it's a setup that really works well for me. I wish you exciting and safe travel!!
Vaya con Dios,
J.T.