Having one camera and one lens if anything makes things 'easy'. You don't have to think about extra gear, weight and carrying 'more'. Your photography adapts to the equipment and you think in a nice compact box so you can concentrate on your experiences and see with your camera in a set way.
I did a couple year stretch on a bicycle and backpacking back in my 20s, and having more was not an advantage, just an M4 35mm and small occasionally used 90mm Elmar (and sometimes while climbing in the Himalaya wished I'd gotten rid of the light weight 90). Since then I've done a few trips with my favorite travel camera, a Rolleiflex and its 75mm lens and never felt I missed much for versatility - 'feet' are wonderful multiple focal length lenses.
Having back-up or a second body with lens has its advantages, but if you are willing to take the chance 'one' can be a beautiful experience. The only 'back-up' I would recommend is a set of small binoculars (like the Leitz 10x25, 8X32 I've used). They are great for 'brain cell photography', and give you a wonderful experience that's goes along well with the camera/lens.