Well, its a construction adhesive so its probably water resistant at best. It's not like it will instantly dissolve when water touches it, but its probably not the best solution as far as long term durability goes in wet environments. As for the strength of it, the adhesive itself is very strong, but it all depends how well it bonds to the relatively non porous surface of the PVC pipe. It will stick to the wood no problem, that's what it is made for after all, but just from my personal experience working with plastics and adhesive I feel the best bonds for plastic come from a glue that provides some kind of exothermic chemical reaction such as an epoxy. So all in all, the glue may work for a while, it may work forever, it may not work at all. My guess is that the glue will hold the rail to the wood, but once you start using skis on it, and you dig in a little, that the sudden force will break it free.
So take it for what its worth, this is all just my opinion.