By all means get one. Get a big whole house filter such as sold at Lowes and Home Depot. The Culligan at Home Depot with 4x10 in filter and remote sensor is about 70.00, I think fittings and devising a stand to bolt it too are just minor details. Filter media well you will find lot of variety and quality on line.
Believe me if you say in Midwestern RV Park with well water you will see the need.
Those tiny in line filters clog up mighty fast and then bypass dirty water to the faucet again. Your onboard house filter is as good as the media in it but it will cog up fast, in a week atone of those campgrounds too unless a pre filter to catch the most.