I went to Dick's Sporting Goods today looking for a drink holder for the trike that would fit the Hydro Flask bottle. They had nothing. As a matter of fact, I was extremely disappointed as they only had the same type that I already have.
I've been looking at other options. I first thought about those cage drink holders installed in sail boats but none look tall enough. But, how about PVC pipe? The larger pipes are thicker. I can make it taller and glue a lids to the bottom. Screws through holes drilled in the side will hold it on.
I'm heading to the hardware store and will let you know if it works.