Fake floor and amp rack help in a hatch

Any ideas or help with designing a fake floor and amp rack/area in a Honda hatchback 97?

Rear seats I'm pulling out, I'm thinking a fake floor (plywood/mdf) in hatch area, where I will be putting one 15 inch sub and enclosure along with a rear speaker box housing 2 10 inch drivers and some tweeters, I need enough space for a kinetik hc 2400 or two hc800 maybe in spare tire well, amps might go where rear seats once were, just trying to draw up a rough game plan here

How would I keep the fake floor in place?
Recommendations leaving amps in open air or making an enclosure with fans constantly flowing fresh air? (Currently car has no a/c)

My goal is to put a clean and tidy setup, not show quality.
Thanks appreciate any input