I used this
Carpet Protection Self-Adhering Film when I did PCD for 135i. It worked pretty good. It wasn't perfect on the car but it helped IMO. Was easily removed at the end of my trip. Had a little bit of glue residue at the edges. Had to use 3M adhesive remover to get it off. But nothing short of regular cleaning bugs and tar off.
edit: i brought wax as well to put on before sticking the film as an added protection so the film came off easily. Kind of like vinyl stickers.