I hard plumbed in a gate valve at the end of the dump pipe. Wasn't too difficult of a job, and it stops the "surprise".
I figured that if I put a twist-on valve, with my luck, it would either:
- Fall off on the road somewhere
- Get stolen
I did find once while doing an inspection of the rig and hitch before leaving from a restaurant dinner stop, that somebody had pulled the handle out on my added gate valve as a "joke". But it was no problem, as they couldn't open the valves in the convenience center, and most likely did not know about the galley handle.