I've attached a screenshot of my boxnotes.
My exterior dimensions with .5" plywood comes out to 1cu.ft. internal.
Probably .92cu.ft. after sub & bracing are installed.

I'll be building two of these boxes for a very particular under-carriage truck application. Firing up through the front floorboards via vented holes.
Depth isn't very much. ~6" depth.
While width is 9" and length is 45".

It will be for an open-air truck.
Tons of digital amp power, whatever I need.

I listen to hard rock and newer jazz.
So I want tight, loud, hard hitting bass.
Which means I'd really like extension to 30hz if possible, but I don't expect it in an open air vehicle with tiny open air enclosure.

Again, it'll be two enclosures.
One under each floor board (passenger & driver).
Each with 1cu.ft. internal before sub/bracing.
With open-air, I don't want anything visible inside the cab.
Think of a Jeep without a top.