You will be unsatisfied with a canister type filter or just a water softener for your high iron water. I know you said you'd like to keep it inside your rig but you need to seriously think about a residential type iron filter/water softener combination system. A small storage shed at your seasonal site could house the components.
There are some small units out there but for the amount of people you mentioned will be using water (and the frequency) nothing small is going to last and continue to work for very long.
2016 Flagstaff 8529IKBS Diamond Package 5th Wheel
Ford F-Series SCREW 4x4
TST Tire Monitor - Sinemate 3500w Gen.
2016 Nights Camped = 42