The thing with seatbelts is that a lot of them are designed with too much freedom of movement and that actually makes them very dangerous. You need one with wide straps and that the harness part goes further down the body, not just around the shoulders, and that holds them firmly to the seat.
I’ve used the water bottle with the fold out dish that’s the same shape as the bottle. It worked great for the dogs, but it didn’t last all that long. A friend of mine got the exact same one and hers has lasted about forever, so I suspect in my case it is a bit of handler error.
