Could you not produce water at home and take 25L tanks with you? Those systems sound handy but as has been said, you need a supply whilst your out and about and it's going to cost a fair bit to run.
You can build your own trolley with quality parts for about half the cost of that lot, then get an RO unit at home for a fair bit less than the total cost of that trolley.
My trolley has cost about £250 and if I had spent a little more time i think I could have knocked a fair bit more off the price.
The more I see of these systems the more I think about marketing one, quality parts brought in bulk or trade and they are making a serious profit.
I think I could get £150 profit out of my system if I sold it at 350 so have a think about building one

Happy to help if you get stuck.