I used two sections of C channel and some flat stock to make two five sided boxes. I put one on each end of the storage area. One is fixed, and the other has the top surface hinged with a hasp. I open it, put the poles in and then close it and put a snap link on the hasp to secure. Haven't had an issue since. The sides of the "C" are about 6" long so there is no way for the pole to slide around and get out. I have two different length sections, one for the top poles, one for the legs. The PVC is nice, but it costs more and I am a very thrifty person(Cheap!). Hope this helps.
Mike