I am also 5 ft and have done a bunch of research on this subject, looking to try out cross last year.

This is a petty good Ryicle summarizing the options and issues. If you google the subject you will find a couple of other forums and discussions just like this one.
http://www.cxmagazine.com/small-cycl...s-short-search

I don't think the crux was avaiakable in xxs last year when I was looking. I would like to see now how that might fit.

I ended up with the Novara Pulse. Cheap kids road bike from REI. I stripped it down and completely rebuilt it to shave 5 whole pounds off it's hefty weight. Spent more than double the price of the bike on new parts, but it was worth it Only the frame is original now, and it works and feels great! My hubby finished building it up last year a week before a crash that broke my hand so I just started riding it and learning my cross skills a couple of weeks ago. So far, so good-first race in two weeks.

Good luck!