[jappgar]

For this use case, old fashioned radio is a lot more reliable.

[toast0]

Quite likely, but then you need to carry that radio. And probably still carry a phone in case you split up and want to communicate.

[subscribed]

You raised reliability issue, you've got a solution, now you're moving a goalpost and raising a convenience argument.

Decide which one is it.

PS Motorola talkabout T62 or T42 - small, light, reliable. Retevis h777: sturdy, reliable. You can just drop them in the bag.