Close your sliding door from the bathroom to the bedroom, and it should be down near the floor there.
Depending on the location of your drain, you might have another access panel inside the rear dinette booth. Take the cushions off, lift up the plywood top to the bench, and look on the wall there.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR