I recently left Florida for NC, but nursed in Florida for almost 20 years. First as an LPN and then as an RN. I have never heard that anyone can challenge the LPN boards, not even Medical Assistants. You will need to go through the LPN training course.
I explored a lot of different options when I was an LPN, in an effort to get my RN. Ultimately, I decided to go the traditional route through a community college for my ADN. I graduated in 2000 with my ADN and am now attending the University of Phoenix - online. It is very expensive, but the courses are accelerated and the time to finish is much quicker than going through a traditional ground university. Don't let anyone tell you that online is not tough! While I am maintaining a 4.0 GPA, I am working my butt off to keep up with the work. It is worth it for for as a single parent.