The Germans who had a decent grasp of logistics had a tough time of it in the western 1/3rd of the old USSR. Very few roads and railroads in part doomed the German effort. (German strategy, which changed frequently, did not help either).
Take a look at the map and even if the Japanese could have jumped off from the middle of Mongolia the logistics would have been nothing short of a nightmare. I would imagine that the road/railroad network in the east would have been even less impressive than what was available in the west of the USSR
Also remember that Stalin controlled most of the news, so unless by some miracle the Japanese were able to effect some sort of major victory. I IMO all the Japanese would end up with would be a chunk of land at the end of a very long supply line.
Regards
alfa6 ;>}
A little past the use by date :-) but along the same lines a Freeper Foxhole article from the wayback machine regards “what if the Germans had gone to North Africa instead of fooling around with the battle of Britain?
http://www.freerepublic.com/focus/f-vetscor/1458006/posts
Regards
alfa6 ;>}