If you got to Lowes, Home Depot or similar look for hollow core door anchors. The brand I use is EZ Ancor. These work very well in those thin walls. Just make sure and drill a pilot hole. I use a little bit of silicon glue (not sealant) on the ancor threads and let them set up for a couple hours before tightening a screw in them. I have successfully mounted a number of items with these. I have a towel hanger in the kitchen which is a 1"X6" board about 3' long with 4 horse shoe towel hangers screwed to it. It's still there so they work as this is heavy.
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