I would think the 2' would be good......that would put you I believe around 13'8", but the 4' wouldn't hurt for an extra 200 bucks.
I considered the Rotary for a while......but the rise height was not enough for me to stand under, even with the extended height (unless it was a truck). If I recall, the rep I dealt with said the cylinder stroke was like 68" for standard height, and 71" for extended. I am 75" tall, and have to squat under even the SPO12 unless its a truck and I use the tallest stack adapters I can fit in there. I do love that lift tho.......rock solid!