Multiple sub placement

To start with. I am not looking for criticism on my gear. Most of it was given to me. I drive a 1996 intrepid. I currently have 2 alpine type r 12’s in my trunk running off an Infinity K1000. Yesterday I was given two 10’s in a truck box. I am going to hook them up just for fun. Should I put them in the trunk with the 12’s? In the back seat? Which way should I fire them? Etc etc etc. they will be run off they’re own amp, in they’re own airspace. Thank you for any advise