As I told my daughter, just cut a hole in a sheet, and go as a "sheet hole!"
Or she could go as "Austin's Sheet". All the sheets my wife buys are the odd Tshirt kind so I finally found the one I had when I was kid. My wife hates it.
I would go with one of your ideas if they weren't so crazy... I had to give away my headdress and am still looking for a cheap alternative. Suggestions?