Trex and other composite have a tendency to sag if they are not supported every 16 - 24 inches. I used treated lumber on mine.
Sounds like to much work. Treated lumber will last longer than the carpet will and that comp. stuff is pricy.
Greg, I through bolted mine with carriage bolts, counter sunk the heads. Layed it all out drilled and installed the bunks. Then removed and carpeted over the carriage bolts. Here are a couple of pics.
JW, the color is House of Colors - Tangelo, unfortunetly I jumped the gun and had the trailer painted before the hull was done being gelcoated. The boat turn out to be different than what was expected.
Greg, the lights came from Dana but I would call Tom to see if he carries that style first.
Shortly after that pic. was taken I got some stainless fenders, ouch they were expensive.
Casters can help save that rear cross member from getting drug.