I believe the only reason they are not used more often is cost. The load carrying capacity is less than dimensional lumber, so to compensate, some manufacturers have added aluminum reinforcement underneath their poly bunk options. On pontoon trailers it is common to add poly "Slicks" on top of carpeted bunks, so the behemoths can unload in shallow ramps easier, but I've not seen them as solely being poly only. Never researched how long carpeted wood bunks last, I suspect about a decade possibly, dependent upon use. By all means give it a try, but shoot for structural support at least equivalent to standard bunks, or you may end up with trailer dimples similar to what can occur with roller trailers. Of the air boat trailers I've been around, the flat bottoms seem to require a different level of support, having more support side to side rather than a stringer based V-hull. Just my $0.02