After banging my head for about an hour, switching up cables, DVD player, and all of that.... I decided to go after the easy stuff. After all, that's what we pay Forest River for... right?? WRONG!!! It turned out that the cable which goes from over the passenger to the main cabin TV's audio was plugged into the wrong inputs on the back of the TV!!!
I first dug into the Toshiba manual to look at the jacks on the back of the TV and noticed that it'd be easy to confuse the audio L/R inputs and could possibly be plugged into the outputs. Sure enough, when I took off the back plate in the bathroom... BOOM! Switched them around and now I have audio from my DVD player! Wham! Another one fixed!