Well, I thought I might try kitbashing some Hinterland Forest wide river tiles, but I don't think I'm going to get far with that idea. If I had the layers that they had used originally, it'd be a piece of cake. Unfortunately, I don't think I have enough texture to make the water wider, and the riverbanks are really curvy, and hard to work with. Keeping everything aligned with a 1" grid is a little wonky too.
At least I had a chance to really look at how the tile textures were made. It looks like they have layers for leaves, grass, dirt, pebbles and water, and they use layer masks to expose each texture. I'd be doing exactly the same thing, but I'd have to try to recreate the texture layers from scraps which just doesn't seem worth it.
I'll focus on other kitbash ideas.