If you use PVC cut the end of the PVC at a 45 degree angle then cut the donkey dick at a 45 and flip it (inb4 any sort of joke) then attach with a PVC cement and reinforce with galvanized screws. Make a support out of wood and then a post going into the ground. For added stability make a crossmember attatched to on of the other supports.
Just an idea.. It would be cheap and easy to try, if it doesn't work then take it off and cut the rail so it's end is even