'68 Globetrotter dump valve trouble

[Randy Gates]

Need some advice. I put a Thedtford adaptor and then a store bought shut off valve on the rear black water tank so I could control the draining process. Got the unit with just a cap. Problem is there is not enough room to attach the hose in such a cramped storage box. What would work would be a 90 degree shut off valve straight off the tank since the bottom of the storage tray drops for access for dumping. Has anyone solved this problem? I have seen angle valves but not shut offs from VTS.