A head-up in VietNam in case you aren't aware.. they now let any size of bike in. Recently a couple on Harley (Electric Glide) was able to get in.. toured Nam with no problem. However, there is only one
border crossing you can enter and exit. You can't enter at this border crossing and exit at a different border crossing. Edit: rules aren't strong so I guess you could check if you can exit at other border crossing- they might let you if you give them some fine wine!
HUBB: VietNam Crossing
I am subscribed to that thread so I can monitor what's happening with this. Also, I believe that Myanmar is now letting you cross? Heck, you probably could tour all over SE Asia countries and still be able to get thru India.