I am look at replacing my bunks on a 20' SunNFun. It is not on its original trailer; it is on a trailer for a 24' Lowe Pontoon. The bunk carpet is getting thin and starting to tear and now 2 of the 2x4's have collapsed due to rot. My thought is welding rigid conduit to the supports and then putting PVC conduit over the top of that. The rigid conduit will never rot, and should something happen, I could slide the PVC off and put another one on. I know there has to be a downside to this, but I cannot figure out what it is. Why are people not taking this approach?