Don,
I can see the need for a lock on the biffy room if you have others with you or a lot of visitors. There is just the two of us so if you can't find the other person, you guess they are in there. Ed usually closes the sliding door when he goes up there so I know he is there.
Happy trails.........................
Sue and Ed Rowe
Hemet California
2005 3400RL
2006 GMC 3500 Dually, D/A, Crew Cab, Long Bed