It seems to me that saying you have a "TT" is insufficient information to determine the TT building material. Our Lance walls in the bathroom shower have aluminium studs or supports, I know because I've had to drill into them. Even at that I believe the other walls with backing and foam would hold most light fixtures such as a towel rack. So what TT do you have?
2017.5 Lance 2295
2021 Silverado 1500 Duramax
USN, Pilot, Retired, Married to best friend 42+ years