Water dispenser sink adapter

We're converting a cargo trailer to a camper, and one of the issues we ran into is running water. Our simple fix was to buy one of the rechargeable pumps that are designed to sit on top of a 5 gallon water jug, plus enough extra tubing that the jug could sit on the floor under the sink counter and the pump could sit on top.

The works okay, but the pump keeps falling over or off the counter. To fix the problem, I made up a quick adapter that fits into one of the faucet holes on the sink and