Having required one on my former TT, it's a permanent fixture on mine...just in case. Also have the DrainKing between it and the sewer connection...just in case the tank flusher can't break up the logjam at the gate. A clear extension on the other side of the valve and then the sewer hose. Even on the low-rider TT, it never got in the way or got hung up on anything.
This past visit up north, I actually had to remove the DrainKing and valve to come to the rescue of an older couple with a SOB. He was trying to dump his tank and couldn't get any flow. And the water was backed up to the toilet. He was on the phone to either his dealer or his son, not sure which, when my BIL (who had been chatting with him) called me over. He was about ready to haul his rig back to the dealer, thinking the valve was not opening. Between the DrainKing and my flexible toilet wand, the problem was solved.