CB400 SF is definitely the most reliable bike i've ever owned,,,absolutely bullet proof.
Even after sitting for a year, charge the battery,drain tank and carbs,refill and no probs at all after 60,000kms.(apart from needing a new regulator/rectifier,,,very common problem but fixed with an after market one with cooling fins)
What i would say is that it really would be a squash two up with luggage.I've done it but the pillion was not comfortable at all.With soft throw over panniers there is no leg room for a passenger.(well not much).maybe with mods you could over come this problem......
Also it isn't great on rough roads (tested all over the West of Ireland,,,which i presume would be a lot better than some of the roads you will be riding) and has a tendency to go all over the place when confronted with pot holes.
It also has a very revy engine so no low down grunt....
I would agree that other more off roading based jap bikes may be a better bet........i see the way your thinking though but outside asia i'm not sure about parts availability? It wasn't too hard in Ireland even though it was an import,
Maybe other riders can advise you in this area????
Hope this helps,