pocket door and wall install

My wife and I live in a 1983 Wycks doublewide on a permanent block foundation. I am about to remove the wall between the main bedroom and dining room (1X4" studs) and install a new wall with a 36" pocket door, which brings me to my question: If I install this door with a Johnson 100721DR pocket door kit, do I need to use 2 X 4 or 2 X 6" lumber to achieve the clearance? There is also a light switch where the door would slide into the new wall, and I feel that if I used 2 X 6" studs I would have enough clearance for the switch (in a UL approved switch box, of course!) Any answers? Thanks!!