Locating Place to Drill Outside Top of Hauler Wall

[BRB Rig]

We own a 2015 Fuzion Toy Hauler and we have a frame with solar panels that we want to affix to the driver's side of the hauler garage, between the LR slide and the ladder. We need to attached four hinges as close to the top as possible (see red arrows) to hold up the 200lb+ frame and panels.

Does an aluminum or wood top plate run across the top of the wall for us to drill into? Do vertical common studs run every 16"? Any help appreciated.