I’ve been traveling with one bag for years, sometimes for multiple months at a time, ranging from tropical islands to the arctic. Some quick tips:

• Pack light. If you cannot carry your full one bag for a day out in a foreign city, you’ve packed too much
• Have your bag with you. Don’t check it in while flying, don’t leave it in a hotel or a train station locker if you can avoid it
• You can do laundry while traveling. Sink wash, use a laundromat, etc
• Layering is key in cold or variable climates
• You generally don’t need fancy gear to onebag, but for example merino is quite practical
• Keep track of what you pack (lighterpack is a great website for doing this). Refine, eliminate, consider what worked and what didn’t

This was my primary device for a couple of years. I didn’t have a phone at all. I could do everything I needed to do. Camera quality was of course terrible, but I had one of those Sony “lens cameras” paired with it, and that worked great.

I even sailed across the Atlantic with the Nexus 7 as my only media device (I packed a Kindle but it died a week in).

That is why I’m considering a foldable now. If only they weren’t so fragile…