fornesto - Our teardrop is 52" wide. We used a heavy material purchased at Walmart in their fabric department. It's almost like a burbor(sp?). It was only $1 per yard and came in 60" width.
Make sure to get good glue. We first tried cheap spray adhesive, and that was a royal PITA. Get the good stuff, get the 3M spray, we also found that at walmart.
Here's a picture of my ceiling and cupboard. (The cupboard hasn't been trimmed on the sides or bottom yet.)
We still have to trim out all the spars, but that can wait. It's nice and bright, helps soundproof, and doesn't get damp when camping in it.
Steve