10" filter housings with 5 micron string wound sediment cartridge followed by a Doulton 1 micron ceramic cartridge would be a very good setup. Doulton ceramic filters can be cleaned repeatedly with a scotchbrite pad and will last a long time. String-wound cartridges are quite inexpensive. Could do this for around $100 -$150 or so including a few fittings.
A regulator before filters is recommended as they can be damaged by high pressure in some cases, but recommended regardless. Pressure can be very high in some RV parks.
Depends on exactly what you want to achieve and remove from the water tho. Carbon block filters remove chlorine but that can leave piping inside an RV unprotected. A POU (point of use) carbon filter at a sink is a solution if you want to improve taste & odor. Chlorine can be on the high side in some locations and bothersome to some people.
Filters with KDF or silver prevent bacteria growth in it but will still pass bacteria through it. Pleated paper sediment filters encourage bacteria growth. A filter with a 1 micron will remove parasites and some bacteria.
I would get filters that are NSF listed otherwise the manufacturer can make unfounded claims or filters may not have any specs provided for them and you won't know what the performance is.
Physically larger cartridges will generally last longer. Some are rated in gallons of use. Quality filter cartridges will have detailed specs.
Doulton has info. on filtration for RV-ers
here.