put your thinking caps on!!

DS and pregnant DIL moved into new rental today. The kids room is just awful!! Black and red painted pictures on the wall. It's on wallpaper, and since it's a mobile home, the wallpaper is glued to the sheetrock. There are quite a few small bad places, holes, nicks, etc.
SOOO, we need a solution to cover this mess up. I tried Kilz, but it still bleeds through. What about plaster? If we used plaster, could you put nails in it to decorate? It has to be something textured, and wallpaper would be way too expensive, considering the walls aren't perfect.
It's to be a little girl's room, so keep that in mind, butterflies, birds, something gardening is what they were going to do.
help!!