well if it was me...i would take a piece of mdf and cut it along the floorpan...where the bottom of the rear seat mounts...and raise up around 4 inches to be level with the trunk floor and cut a piece of mdf to fit...you will have to do probably 3 pieces...then do your sides and carpet it all...

its not too hard...any stereo shop should be able to handle it...

im in hampton otherwise id do it for you...