Michael, I never underestimate anything about you my friend!
and thank you for the kind words on my patchy summary, which are simply from scribbled notes as this isway out of my field.
All I can recall is that there are two huge leather cannon in Tibet captured from Nepal in some museum, and there are questions on how functional they were. In the same campaigns it seems the Chinese forces were using some kind of leather cannon.
It goes to the mobility issues, and of course the British in the 19th century were striving for the same kind of mobility, but using conventional cannon that were dismantled and carried on pack mules. These were the 'mountain guns' and its hard to imagine these poor beasts trying to haul these things into the defiles of the Khyber or Hindu Kush!
All the best,
Jim