ford f150 supercrew under seat sub help

[Briggiboy33 2]

my friend is looking to build a box and install a sub under the back seat. we don't have the dimensions of our space but we were wondering what a good sub would be that is 5" or less deep. were thinking one 10" or two 8" subs in a sealed box. or one 8" in a ported box. any recommendations would be very appreciated. we will be able to fit a 1cuft box according to the stealth box that is sold on crutchfield. 

[Quentin Jarrell 671]

What will fit will greatly depend on the year truck and the installation skills of the builder.

[Briggiboy33 2]

its a 2009 and the installer will make it fit if its possible.