Does anyone think you can water-bath can this recipe?

The Food in Jars website has a canning recipe for Meyer Lemon Syrup which would be extremely similar. https://foodinjars.com/recipe/meyer-lemon-syrup/
I've used a few of the recipes from her site, and found them reliable and safe.

Yes, I think you can. Here's WA State University extension program instructions for a berry syrup, which should work for the lemonade concentrate:
https://s3.wp.wsu.edu/uploads/sites/2053/2021/06/Preserving-Berry-Syrups-at-Home-FS238E.pdf