Play one while camping?

Yes the Bridge does create a dedicated network for your Sonos speakers. However, the Sonos Controller App stored on your Tablet or PC requires WiFi to communicate with your Sonos Network via the Bridge which is why a router is required. Click the link to see how a Bridge now replaced by a Boost interacts with your Network.

https://sonos.custhelp.com/app/answers/detail/a_id/3046?_ga=1.115978246.1617335766.1473897203

Assuming you can get a gas generator to create electricity to match your home electrical current here's a wrok-a-round. This assumes you are actually camping in the woods not in a cabin with amenities :8

If you are in a cabin with amenities (i.e water, elcetricity and internet access) the same procedure applies sans the generator.

Take a PC, Router and Two Ethernet cables. Configure the router for Wi-Fi just as you would at home using the PC and Ethernet to connect both. Be sure to encrypt the Wifi signal. Plug the Bridge into a port on the Router as shown in the diagram using the second ethernet cable. Turn on the WiFi for the device that has the Sonos Controller and music to join the network you created (this may be the same PC). All music must be resident on the device. You will not have internet via the router so make sure all Sonos components are up to date before you leave home (unless you are in the cabin with amenities) :8

Cheers!

Thanks Aj, so this isn't a way of connecting my Play 1 to my phone if I'm camping?

I've got an iPhone, will it work on a personal hotspot?

In theory I guess you could use an iPhone as a personal hotspot. However, a hotspot depends upon a Cellular connection. As you know Cellular is not always a stable signal. Sonos requires stability. I've never tried it personally. As you are contemplating it you might do us all a favor and try it at home and post back with your results 🆒

Here's a link to another discussion on using a Phone as a hotspot for Sonos. Lot's of trial and error IMO:

https://en.community.sonos.com/setting-up-sonos-228990/how-do-i-setup-my-system-to-work-with-mobile-hotspot-41682

You can use a hotspot but the hotspot can't still be the actual controller. So if your using hotspot on your cellphone you can't use that cell phone as a controller and must have another device to act as controller.

Thanks for your help guys, I'll give it a go and let you know.

Either way the Bridge won't be of any use to you, it's disabled when in Wi-Fi mode. You'd need to set up the connection to the phone's hot-spot before you go away as well.

Could he take his router with him (or a travel router set up at home first) , then control & play music locally stored on his phone?

Yes. As long as music on phone.