Well, I'm a happy "camper" this morning. I never thought of hardware stores because, when we had our popup camper a few years ago, I tried them when needing a spare key for it. I finally gave up after stopping at a couple of stores in the area. No one had the blank.
We just had to run out to our DD's work a few minutes ago only a couple of miles away. I picked up her car so I can replace her brake pads while she's at work. There's a Town & Country hardware store just down the road from her work. $2.12 later, I have a spare entry key!
Thanks for all the suggestions.