First thing is to learn where YOUR plumbing goes. (mine goes low, along the floor wall junction, so odds of hitting plumbing other than the stink pipes, very low)...
Electrical is another concern.
Suggest NOT hanging outdoor TV.
Most RVs the walls (interior) are not really good for hanging stuff less you can find the studs (easy to do in some areas) and drill into them.. If you drill into a stud you will NOT be hitting anything other than stud.
To find studs you need the proper weather conditions.. In the morning, after "dewfall" there is often a short period of time when the "Ribs" as it were are clearly seen, Streatch a long tape measure along the side and PHOTOGRAPH.