You tune the sealed enclosure for a .707 - .80 Qtc. and add the EQ. This will definitely require a very linear driver such as the afformentioned audiopulse or something like the W7 drivers from JL.
Vented enclosures will allow the lower tuning, more output, and much less EQ but at the expense of a substantial increase in size.
Everything is a set of compromises. It is simply choosing which ones you can live with and those you can't live without.
Subwoofers, for the most part, do not require extensive testing equipment though they make the job easier. Freeware modeling programs such as WinIsd allow for very accurate enclosure design using the T/S parameters of the woofer.