took back seats out, need more room Options

[FSX_Celica94GT]

so i took my back seats out over the weekend cuz i need more room to put stuff since i have a giant sub box in the back of my car. I need more room for my back pack and computer when i go to lan parties (noone ever sits back there anyways), but my question is, since theres absolutely no carpet underneath the seats and theres 2 dips in the back where the seats were, i was wondering what would be the best option to fill this in with? i was thinkin about gettin some carpet and just putting it back there, but then i decided i was gonna move my subs up so i can have an easier time getting my backpack out. Maybe a thick board cut to fit the back would be best? what do yall think?

[popstar]

ok !

first line the seat dips with cling film or a sheet of polythin, then fill the dips with expanding foam and cover with thick card. you now have a removeable pack for you seat well

then cut some ply wood (MDF would be better) and cover in carpet to fit the space which should also now be level with your trunk,,,,,

good sound insulation for the music and good load space .....