To do it with out raising your seat is hard. That was my plan but I had to end up with forward face like I did but I have an 03 and forget how the 08s look but the crew cab should help with available space
I have 2 10" XFLs with about 2.75 box with dual aero ports. You can't find a ported under seat enclosure online and built my own and would recommend it, its cheaper and you known it will fit. The xfl is deeper than most 10s and even 12s. 2.75 is a great amount of air for a under seat and no raise. Mounting depth and recommended air volume are the 2 main things to look atI don't mind raising the seat. What subs are you running in yours?
I have 2 10" XFLs with about 2.75 box with dual aero ports. You can't find a ported under seat enclosure online and built my own and would recommend it, its cheaper and you known it will fit. The xfl is deeper than most 10s and even 12s. 2.75 is a great amount of air for a under seat and no raise. Mounting depth and recommended air volume are the 2 main things to look at