I do not store the tank draining hose in any storage tube on the trailer. I have found over time that the tubes will rust unless plastic and cause the hose to wear as they are dragged from the storage tube on the trailer.
I store mine in a Rubber maid bin with a lockable lid in the basement of the trailer. The bin is marked waste and is large enough to keep the drain hose and clear elbows along with the hose connections. Every thing is right there where I need it and handy to get at.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67