I had considered the above F800 / RotoPax setup for my Jesse's and of all the options for permanent installation it seems to be the best solution for capacity, weight distribution and just straight out being out of the way.
Ultimately my concerns were and still are:
1. Safety - On the few spills I had on my F800 the lower front corner of the Jesses always took the hit, they survived plus protected me and the bike. However, I never took a hit on pavement and the position of the RotoPaks located in this lower position pretty much guarantee they're going to take a hit either side.
2. Support - The geometry of the Jesse's make them extremely sturdy but the metal itself is thin. If I were going to mount low fuel packs I'd insist on not just mounting through the bottom with a large fender washer inside but into a long lateral support bar or plate inside the bottom of the bag to distribute the load, the same or similar to what Jesse uses inside on the side mounting brackets.
Ultimately I never did a mounting solution and simply went with two 33oz MSR fuel bottles for $15 each. That was more for emergency backup than extending range and the only real use I ever got out of them was helping stranded Harley riders who ran out of gas on the freeway