A couple of other boat vs RV points. Generator prep does not mean much. The wiring is there. A tin box is built into the 5er basement. NO sound shield. The noise complaint is not only how much you hear inside, a hum or roar depending on lots of things, but also the exhaust noise to others in the CG. Never welcome. The noise is not muffled by coolant water like a marine genny.
Internal vs portable genny for a 5er. The vast majority of us get along just fine with a lightweight small 2000w inverter genny. No, it won't run the A/C but it will run everything else. It is far cheaper to buy than the built in, is much quieter & burns far less gas.
The facts are, you are far more likely to be spending time in a CG hooked up to shore power than to be out on the land hook. Readily available 'anchorages' do not exist & no, you cannot spend days at Walmart. Every 5er has a furnace however most of us have portable heaters & use shore power rather than burn up propane when we don't have to. RVs are terrible at heat loss. You can't close them up like a boat. Heat & cold gets out around the slides. Their bottoms are not sitting in insulating water.