I would have a 100 foot heavy gauge extension cord in your stash for those times that you "need" it. I carry a 12 gauge extension for those times. Also, a Y hose connection for those times that you get a spot where "others" have left you no hookup for water without adapting. Throw in some spare hose washers. In dryer climate areas one does not like to see leaking hose connections. In your tools you should have a multi meter for checking circuits and continuity. Nitrile disposable gloves are handy for handling the dump duties. Don't forget your rain gear for those days when unhooking has to be done in the rain. Always slope your awning for those rainy days and nights. Put your awning in when faced with windy days to avoid damage. Pickup one of those toilet cleaning brushes with the disposable cleaning tips.
To darken the interior for sleeping we have always made covers for our windows to keep the light out that we always seem to experience whenever we park in a camp or boon docking like at Walmart. We attach them with plastic clips. They make a world of difference for those of us that have difficulty sleeping with a "light on".
When hooked up in a park it is advised that you do not run the tanks open. Best to fill them up and then dump to avoid any issues when necessary. Also, many parks do not allow temporary connections and mandate that all hose sewer connections be air tight for sanitary reasons and courtesy to the campers next door. We stayed in a park in Coty, WY where the sewer gas was nasty. Looking around we noticed many campers with open connections FWIW.
Sometimes you get s spot where the sewer connection is above your black tank connection. It happens. Do not try to dump as you will have a messy situation on your hands, literally. Best to move or just use the dump station when leaving if convenient.
Much of this you will pickup on the road. Good luck and have fun.