It is a tricky one, I am also getting used to the whole idea but I am very impressed with the little Nomad Bag! I will be using it again when I am going to my parents in Yzerfontein for the weekend.
Straps play a role, my friend swears with ROK straps but that wasn't in my budget at the moment:
I went to my local Spiro's and settled with the R90 pair of ratchet straps which worked for me greatly so far.
Another bag option is maybe this one:
My friend got it for his BMW 800 and offers a lot of space. He then uses his top box for food storage.
On our previous trip, I only used the 26L Nomad bag which I used strictly for clothing, toiletries. I made sure to only pack the stuff I will require later when arriving in the camp place and since we stopped at shops, I did not want to leave any valuables in that bag. So tools and valuables I split between my tank bag and backpack, in your case, I would keep the tools (if not too bulky) in my tank bag and my camera kit in my backpack, along with chargers and accessories.
Returning to packing, it is an art form and my first attempt also needed rethinking and going back to the drawing board. Also, I think packing lightly is keen as well - something I quickly realised.