An interesting concept this system.
I would not want to haul that around on a trolley!, it would be better off mounted in your van all the time, and if you have a van why not fit a tank as well? Not every customer has a guaranteed high psi water outlet.
If you are going to fit a tank as well you do not really need such a fast production rate, so you could probably get away with a much cheaper Ro system.
For interest this system only produces just over 2 litres a minute, a Merlin on 100psi input pressure will produce between 2 and 3.2 litres per minute and is a lot cheaper than the above system.