I use this kit - https://www.amazon.com/gp/product/B00BDEPJ1W/
I don't see many other campers use this type of hose, it's ridgid rather than flexible and that is what makes it so universal. Only use the length that is needed to reach the drain. It makes straight, short rigid span to the drain with no curves or bends to slow water flow.
Each hose stretches out to 10ft, collapsed they are 36" each. I keep them separated in the rear bumper and access them from each side of the trailer. I have never needed the second section but I did loan it to a fellow camper once that did not have enough hose to reach the sewer drain.
Like others have stated carry 2 x 25' fresh water hose. Most times the 25 footer will do the trick but on occasion at older COE and State Parks water can be more than 25' away. Save yourself a trip to Walmart after arriving at camp and carry a spare.
I have been to a few parks that have "Community Water Hydrants". These are spaced out so 3 camp sites can use one hydrant and are usually between 50' and 75' to the camper. I usually carry a 50' garden hose for rinsing the truck or trailer off on occasion. The garden hose comes in handy for the community sites.
If you do plan to stay at parks that have community water be sure to bring a Y-splitter so the next guy can connect his water hose to your splitter and the next guy connects to his splitter etc.
As for the power cord, the factory cord is usually enough. I have a 25' extension that I use to connect the trailer to shore power while at home. I have only needed the extra cord 1 time at camp but always bring it along just in case.