Can you put a car subwoofer on its back? I have a big ole 15" now and it takes better space laying back.?

I have a big ole 15" now in a hatchback that I used to use the cover on my 12". That slider cover so people don't know what you got. I know the bass might not bounce off the walls and resonate as well but until I get my windows tinted I would like to conceal it if possible w/o damaging the speaker.