It used to be that non-pro drivers paid $12 for showers at the Flying J on the east side of Yuma. The last two times I was there they waved away my cash and said, “Give us your driver license to hold until you return the key.” (This is an older place without fancy digital door locks on the showers.) And it all went just like that.
This isn’t my favorite truck stop for showers. The towels are thin and scratchy and the bath mat is a piece of paper. But hey, it’s free. At the moment, anyway.