What provisions are already on your trailer for a power cord? Casita
uses a standard 30 amp RV cord hard wired to the converter. There's a hatch on the side of the trailer with a cutout just large enough for the cord. The cord is stored into the area behind the converter.
Wal-Mart has 30 amp RV extension cords and you could cut the female end off to hard wire it. Or you could mount a hatch cover that has a male 30 connector that would allow you to disconnect the cord and store it somewhere else. Or forget it.
Walmart 30 amp 30 foot RV cord for $45.
Road Power 09570-75-08 10/3-Gauge 30-Amp RV Extension Cord, 30-Feet - Walmart.com