From experience travelling and making these choices - I suggest 2 cameras, one lens each.
As others have noted, the Mamiya 6 and a 35mm.
Less is more. In that it's a creative spur for you. Don't sweat what you'll miss having 2 cameras with 1 lens each (you won't miss anything!), realize instead that you'll miss more fumbling for lenses and making that choice...you'll be less open to what's actually around you.
Don't worry about it. Go light, cover yourself, and truly live this trip. I'm not a betting man but I'm willing to wager if you take this approach, you'll look back on it as a truly satisfying experience, creatively and personally.