What's your favorite thin-wall anchor?

A Molly Anchor. You can Google as easily as I can.

A couple of nice looking 1x4s, suitably stained, jam-fit between the floor and ceiling? Maybe dress it up with a knick-knack shelf above the mirror?

But seriously- just like a real wall, you need to aim for whatever passes for a stud in there. A mirror that small, if you don't care about trashing the wall, you could probably glue a backer board to the wall with construction adhesive, and mount the mirror to that.

aem sends...

DAGS: "mobile home wall anchors"

Gets ---

Get a roll of Velcro with glue backing and cut it into long strips. Put them in a oven at around 100 degrees for a few minutes. Apply to the wall and to the mirror. Let cool and then mount the mirror. Be sure the surfaces are clean before applying the Velcro.

Small toggle bolts is what I usually use for 3/8" sheetrock

I second the Molly anchors. I use them in my plastic shed to hold up plywood which I use to mount hooks and shelves.

"A Molly Anchor. You can Google as easily as I can."

I'm not a fan of the Molly "system." The torque needed to "set" them often exceeds the friction against the drywall board.

The very simple plastic sleeve works much/most of the time.

My favorite is the plastic anchor that has wings that pop out when you seat the anchor via a 1/4" (nominal) diameter hole. The screw causes the anchor to clamp the wall board against the fixture you are installing.

If the wall board was been damaged from a prior installation of an anchor, the toggle bolt systems almost always work.

When I hung some shelves I popped off the paneling and put some propper blocking in .That's the way you keep things from falling down. Jr

Mobile homes usually don't have 2" x 4" wall construction. You're lucky if there is an inch of space in the wall. Not a lot of room for the butterfly to open. That's why I suggested the Velcro.