I need to build an enclosure for a 15' L7. Some of the details...

Dimensions: 26 x 30 x 14 is as far as I can go. With my calcs, external volume is 6.32 ft^3 and internal volume is 5.051^3 without sub, ports or bracing.

Seems right on the money if I follow Kicker's street vented box (4.5 ft^3 + port and the port is 3x16.25 in and 14.75 in deep and comes out to be .42 ft^3 making a grand total of 4.92 ft^3. But tuned to 33 hz that is.

Now here are my questions..

1. If I want to tune higher, say 35hz, how do I calculate port length?
2. The kicker street bass box has the sub firing up and vent on the same end. I am nervous that my hatch is going to fall apart with that setup so thinking about moving the sub toward the cabin (firing up) and keeping the vent at the bottom end of the box. How do I calculate port area?