Not a fan of RO for RV. My company had 200+ RO water dispensers in various offices. RO is high waste and really unnecessary for filtering potable water. I would recommend it for non potable water because of it's ability to remove tiny viruses and such. (there are better methods)
Why did I decide to switch? I began finding large amounts of bioslime growing in reservoirs. I switched to UF and the reservoirs are always sparkling clean at service intervals.
If you have RO, it is very important to change the carbon pre-filter frequently. The chlorine in municipal water will damage RO membranes and the carbon pre-filter is the mechanism for removal.
In fact activated carbon is hands down the cheapest most effective broad spectrum filter. I don't recommend faucet filters or pitcher filters, but they are better than nothing.
We sell a compact 4 filter system that is thorough. If starting with contaminated water, I would add a UV light to kill bio organisms. But don't think a UV light does filtering, it does not.