From Co-Motion's website, there does not appear to be one in South Florida.
When we were shopping for our Co-Motion Robusta, I was looking for a dealer in Florida. I found a couple in Central Florida. In talking with them I found that 1) they didn't stock tandems that we could test ride, and 2) didn't have any particular tandem expertise.
Thus I didn't think they added much to the value proposition. Certainly not enough to justify repeated drives to Central Florida.
I contacted Co-Motion directly (ask for Gary, he was very helpful). I learned I had 2 additional options: 1) buy directly from Co-Motion, and do the measurements and final assembly myself, or 2) buy it through my LBS.
As long as your LBS is willing to work with Co-Motion, and there are no other dealers in the area, you can buy through your LBS at the same price, and have them do all the measuring, set up etc.
Even though my LBS hasn't sold a ton of tandems it all went very smoothly, and we've been very satisfied.
If you have a good relationship with a LBS that you like I would work with them.
Alternatively, if you want to test ride, and want the benefit of working with folks with a lot of tandem knowledge I'd fly to Alabama.
IMHO, I would not bother with a dealer that does not stock tandems, or sell many tandems that is a 3-4 hour drive away, just because they are Co-Motion dealer.
FWIW, our blog has a bit about our Co-Mo buying experience.
http://everestchallengex2.blogspot.com/