The only reason I got my stinky slinky free was because I ran my PDI so long that by the time we signed the papers and sealed the deal, the store was closed..... so they just gave me one.
I already had the potable water hose from my popup.
I think the surge protector is a great suggestion, but overall, I suggest keeping things simple.
First few trips, you'll need the simple stinky slinky hose to drain the waste tanks, a potable water hose, bed linen, food, and a notepad/pencil to make lists of other things you think of. That's about all you need.
The other stuff depends on your style, where you go, etc....
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