A few years ago, after hearing the Scamp electric cord storage port referred to as a "mouse hole", I made a foam plug which fits around the cord and inside of the storage port.
I took a short piece of pipe insulation foam with the correct ID and built its OD up to the storage port's ID by simply glueing layers of foam together until the plug fit snugly into the port. I slit the foam half way thru so it was easy to slip onto the cord after pulling out the needed length of cord for the that camp site. After the first use, I promptly made a handle for the thing out of a piece of duct tape so I can pull it out of the storage port. (In order to control your stress level, I highly recommend you put the handle on the thing BEFORE using it the first time...LOL) Have used the foam plug for over a year now and it is working great.
As an aside...In the previous eight years of Scamping all around the U.S. and Canada, before hearing that descriptive term, I never thought of the cord port as a "mouse hole". I did however think of it as an access for spiders, ants, and other crawlly critters. I sprayed the cord with bug spray to prevent that occurance. Still do....We were warned by an RV park owner in the deep south during our first year of Scamping to spray or powder every contact area of the trailer with the ground to keep their ant infestation out of the trailer.
Our "Lil Critter" has now rolled over 210,000 trailer miles and is still going strong..Nov.18th will be 10 years since she was hatched at Backus and came to live with us...love our Scamp!!