What about an E-Z on vest?
If it is of any help, we currently use an E-Z-On Vest (102PB model) and find it very easy to use. We currently use the vest with the ‘tether mount’ system.
The tether mount requires the lap belt (be it a lap-shoulder belt converted to a lap belt via the use of locking clips or simply a regular lap belt) to be buckled and unbuckled each time the vest is used. This might sound like an arduous task but it is in fact a much easier and more fluent process than it sounds. The loops sewn onto the vest through which the lap belt is threaded are a very workable size and allow the belt to be buckled quickly without any hassle. In our arrangement, the vest simply remains hooked to the tether mount at each shoulder strap and stays in the vehicle; much like a regular car seat would when installed. Overall, the process is no slower or more complicated than buckling a car seat or booster.
We also used the 103Z vest before we had the 102PB vest. Being a back closing vest, it was required that the user put on the vest before they entered the vehicle. The only difference to the procedure when using the 103Z vest is that each shoulder strap must be clipped to the tether/floor mount each time the vest is used. But this takes all of 5 seconds (if that) and is not at all inconvenient.
I hope that provides some useful information and if you have any other questions about the vests I’ll do my best to answer them.
Gary.