^^ Some Canadian cardlocks accept credit cards, even U.S.-issued cards. For example, one in Lynn Lake MB (about 300 km on MB 391 from Thompson, though gas is also available in Leaf Rapids -- I couldn't use that Co-op cardlock machine by myself, but the Co-op store across the street was able to help me).
In Yukon, there was a cardlock that didn't take credit cards. Fortunately, the guy behind me in line for the pump had the necessary card. I gave him a C$50 bill, for him to pump that much gas into my truck. (Not the only situation in rural Canada where Canadian cash came in handy.)
Expect cardlock pumps to be unattended, but Co-op pumps sometimes have someone available to assist, like the one in Leaf Rapids MB. Co-op seems to have pumps and a C-store in Coronach, though that is a long hike west from Estevan. And yes, Co-op will cheerfully sell stuff to non-members.