On the logistics question, what about World War II?
Suppose that after the shock of Singapore when they began construction on the Ledo road, with the expectation that Burma would be overrun, Stillwell insisted on a further backup route. After all, the furthest Japanese advance in northern Burma did eventually cut off the Burma road even with the Ledo road. I'd be surprised if anyone thought it was impossible.
Assuming Stillwell demands a backup, the only real option is "over the hump". They couldn't build a road through there, but I imagine expanding the airfield in Ledo or improving road and rail near it probably could do something to ease the logistics. [Feel free to correct my ignorance if the limits were something else - pilots or airplanes or whatever.] Postwar any extra capacity could easily go to waste, but as a secondary POD let's say the late Empire or (more likely) the early Republic of India place 2-3 small outposts on the frontier beyond what existed in OTL and supplies them by air drop (or maybe a small airfield).
The Chinese begin construction of new and/or better roads up from Yunnan towards the same region in 1950 as part as the move nab Tibet, and especially after annexing the place. It's not done out of any particular focus on India, but because sovereignty demands borders be guarded on both sides.
An optimistic Nehru might in turn see the potential for a direct Indian-Chinese road to be a symbolic if not a practical link, and put some money towards developing a proper road to the border. A road which the Chinese would sooner or later feel obligated to match, for very different reasons. This would all be a low-budget sideline, but I think it's more or less plausible.
A decade later you could supply a much larger conflict in the region, and the Indians might be more hostile, with roads they expected to link the two states used against them.