If you are replacing the cable because of wear, cracking, or a bad plug the easiest way will be to open up the flooring just above where the cable goes up into the trailer. At that point you can cut the old cable, which should be GOOD at that point, and connect your new cable. You will most likely find several feet of cable wound up under the floor so you will have enough to bring the 2 cables up above the floor into a junction box. I say this because it is against code and just makes no sense to hide a connection under the floor.
If you do not connect at that point it will be very hard to work the cable up through the body to the fuse panel
If you live in an area that gets cold make sure you buy cable that will remain flexible at temperatures below 40 degrees. Not sure why Airstream uses that stiff stuff.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles