You should put your rig description in your signature.
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Before buying a water pressure regulator, make sure your RV doesn't have one already built-in.
A roll of Etrenabond and a tube of Dicor self-leveling lap sealant will take care of any roof leaks.
Get some electrical contact cleaner and a pack of emery boards for cleaning out the pedestal plug.
We run a cheap Camco blue water filter for particulates (mud, rust etc). We filter drinking and coffee water in a Brita pitcher.
2-20 lb propane bottles should be plenty for a weekend. Most private campgrounds have propane.
A DVM (digital volt meter) will come in handy when things stop working.