Dynafit Race Thermo Bottle
Great bottle carrier for a knapsack shoulder strap. Only small gripe is the crossed webbing under the bottle isn't entirely centered. Other than that, it's so good I purchased two of them.
Seems to be a great solution for what I was looking for. It took some getting used to having the bottle in my arm's range of motion but having accessible water without using a bladder system has been working out great.