I haven't seen it done to a Versa, but I have seen some neat designs. My 2 favorites are a bandpass so the sub is completely protected by the box and nobody could see it. You'd have to use fiberglass in the wheel well and raise the floor about 3-4 inches.
The coolest design (I'll try to find a picture later) I've ever seen for a spare tire box was where the owner swapped the spare for an aftermarket rim, either a 17 or 18" size. The box was shaped like a cylinder and fit inside the wheel. The wheel sat over the sub so that the face of the wheel worked as a grill.
This is a little similar:
http://www.europeancarweb.com/features/ ... to_07.html
Or run a pair of 10's on the sides in glass boxes. I'm extremely happy with the sound from mine.