It is entirely up to you. Click on my avatar and look at my album.
You use short screws like 1" and smaller when mounting to a rear seat.
133whp-126ftlbsTQ Eclipse CD8443,Eclipse PA5422, JBL GTO751EZ, PPI 356cs(Rebranded A/D/S 346cs), JBL p1024, SubThump enclosure, RAAmat BXT, Damplifier Pro
Hatch Nation #140
Caeci caecos ducentes