I'm posting a little late but I don't know if your TV question was ever answered. On our Jensen system, you have to turn on the TV, go to the TV menu and select AV, otherwise the TV doesn't know what signal to look for.
As for the shower in the RV, -- MOISTURE -- especially in the summer. We squeegee our walls and floor of the shower after each shower. Even with the exhaust vents going, you want to minimize the amount of moisture accumulating on the walls and everything else. We also take our towels and washcloths and hang them outside to dry when possible. Put a tub of damp rid in the corner of the bathroom too. As a side note, if you're paying for elect and propane, you're paying to heat water that you may save $$ on. That being said, I prefer to use my own shower too.
Mark, Vicki, & Scout THE dog
2015 Hemisphere 282RK
2010 F250 Super Duty
1992 Goldwing Aspencade