I can only say that Verizon works well, which I know isn't your question, but maybe someone you are camping with has it.
We also have Verizon and it worked well when we walked up the hill away from the campers.
With AT&T, You'll get 2 to 3 bars most of the time but it does ping off the bell mobility cell tower on the other side of the straight in the Sooke BC area... so just turn your international roaming off.
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