Seriously, there is absolutely no flex in most of my walls. that layer of styrofoam won't let the skin move even a smidge until you reach the point of pressing so hard something is being damaged. My interior walls are easy to work with by thumping and flexing. The places I do feel flex in my exterior walls seems to be where the frame is. There is a little hollow space there. At least that is what turned out in one situation. I had to drill a second hole to hit the center of the frame. The other one I filled with wood filler but it shows. Don't want too many of those.
2008 Dutchmen Kodiak 27CDSL, 94 Dodge 4x4 Cummins, Trailer mods: Automatic switchover for Honda EU3000IS generator w/extension plug to back of truck. Propride 3P hitch Plan to do mods for camping in cold weather.
Right on Mickeyxx -- that is the way it will probbly get done. I bought a new Zircon i700 stud finder because it had a metal detection mode which would be an improvement for my house projects. I think it would do fine detecting the metal in the trailer but it is so big I kept running out of space to slide the finder. It can't locate the metal accurately enough for you to be able to drill a hole and hit it until you have scaned from the left and the right. Somehow it takes an average and homes in on the stud by repeating this process. There is a cabinet or something to hit just about everywhere but at least I can confirm that I am approaching a metal beam and use a bit of logic and press a little here and a little there as you say I would say the stud finder helped but still have to feel it out and take a shot. I missed one and had to get up the courage and move over a bit and drill another hole.