Personally I havent done this crossing, however when I was at JJ in Nairobi I talked to a couple of people that had done this crossing. There are two options, either negotiate a crossing in a boat. Or, ride inland so many km (sorry I can not remember anymore) and take the new bridge! Yes a new bridge - however I think the catch was, its a long and sandy route to get to the bridge.
Customs in Tanzania and Mozambique are good everywhere no matter how big or small the border is. I think I managed to cross a total of four different ones and never had an issue.
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