- Mobile hot spot (bring your own internet! Nonprofit pricing for a Sprint, or commercial through TMobile)
- USB cable to tether your phone for internet & extra charging. Anker cables have a good balance of price and quality.
- USB battery pack (I like the Jackery battery pack b/c it supports lighting & micro USB and has a flashlight built-in
- Medium paper clip for holding papers AND ejecting SIM cards
- Faraday bag (I like this model)
- Noise cancelling headphones (Wirecutter breaks it down and has some pricey models; I'm fine with these).
- 3.5mm earbuds with microphone (in case your noise cancelling headpones are uncharged or too conspicuous)
- A bag. I'm loyal to Timbuk2 but the Wirecutter has some good bag suggestions. I'm finding the backpack my preferred form-factor as the messenger been cumbersom at airports & borders.
This bullet list is just that, a list of things I've found somewhat helpful and doesn't factor-in security considerations.