SD-2 8s and 10s have nice sealed box requirements, and really shallow mount depth. Just did three tens in a Mercedes C300 in a half cube each sealed before displacement. So like .42 cubes net. It plays great and doesn't back down from the 30Hz notes like some smaller sealed box configurations do. The WinISD plot looks like garb if you model it which I know some ppl have used as an argument against them to which I say that you can't just go by a seriously guesstimated generalized frequency graph. Properly positioned or loaded these are pretty handy little beefcakes.
If you want to use that little airspace for a 10" SD I would invert it. But a 8"er would be plenty happy in that space.