Like drmopar, we use a milk crate and store in the front compartment. The square foot print maximizes our available storage area.
When at a campground we simply place the crate on the ground and pull out what we need to connect and leave the balance curled up in the crate. The crate has natural holes in it allowing for rain water to flow out.
My wife also made a vinyl cover for the box which is aesthetically pleasing to the eye.
SILICONE
One little hint that works on all rubber surfaces cords, 30amp or 50 amp. These units especially when new tend to have a sticky outer surface which makes handling a little more of a challenge.
I spray mine with silicone, not WD40 or other oil base lubricants that can deteriorate the rubber casing. This eases the material and aids in it sliding a little better in place. Silicone also does not seem to attract as much ground dirt.
Enjoy your new coach and welcome to the "Extension cord WRANGLERS".
GPG