JMO, I wouldn’t mount a bracket on the exterior. Most likely there is a piece of wood sandwiched during the bonding process. A stud finder may work, but you only need to miss once to have a hole that can be a mess.
I wonder if the old trick would work in this case. If you look at the exterior of a trailer in a brisk morning, you can see all the outlines of the framing in the moisture, may be worth a try. I don’t really care for neighbors that force me to listen to their choice of show or movie.
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.