I stongly advise NOT using Cobra replacement carpet. The failure mode for Cobra carpet is the rubber backing. My carpet started falling out of the top of the trailer three years after the trailer was made. I reglued it but the failure was the rubber backing and the carpet fell down the next year.
Use indoor/outdoor carpet and you should be golden.
However...make sure to remove all the old rubber backing and glue from the trailer before placing the new stuff.