Teardrops n Tiny Travel Trailers

I'm starting on a 6'x13' teardrop shaped camper on a dual axle trailer. It will be roughly 6' tall inside. I stopped and bought some 2"x2" lumber for studs and some thin plywood to frame up the side walls. I've been browsing through some of the build journals and noticed that most side walls are made from thicker plywood and no studs. Since my camper is bigger I thought I would need the studs. Now I'm not so sure. I plan on covering the outside in old barn siding. Any advice or suggestions would be appreciated.

Osage Outlaw,
I am about to build a similar size trailer. What was your decision on the wall construction?

3/4" × 1 1/2 - 2 " should be more than enough if you glue the interior and exterior skins to it