Since you are a former bass head you will probably want to go with ported enclosure. Tuning in 30s, make sure you have airtight enclosure, sides in golden rathio (0,62:1:1,62) round port diameter around 4-5 inches, a few damping mats on the interior walls, Foam on at least three sides (below the sub, on one side wall and on the let say back side - this will reduce enclosure ringing. Take care of port placement, which should be for at least of port diameter away from the enclosure walls and behind/in front of the port. Put some braces on enclosure walls and between the top/bottom/side to side of the box. Position braces on the walls asimetric - that way you will get two different areas each with its own resonating frequency.
Next thing is to position enclosure in the trunk in a way it will give you the best output (loading)
put somekind of gasket under the driver to decouple it from enclosure
Use speakon or similar connection posts - dont route cable trough a port
When designing enclosure opt for smooth impedance curve
aim for low air speed trough the port
use aeroport endings - shorten port tube for the 1/2 of height of EACH aeroport ending used to get very close to desired/calculated tuning
put the port on same side as driver is installed