The new bridge is low, however, i think, it is possible to get F27 under with mast down. However, it will be very tough job to get it to checkpoint. It is located in side creek, narrow and shallow.
Are you seriously considering taking F27 into EC? How are you expecting to propel it? How's about getting it onto the beach and from the beach at the start? No outside assistance allowed. There are changes in beach start for the next year, I don't remember them all, since I've never carried about it with my light boats, but there are stiffer rules now, making it much harder for bigger boats.
I don't think that the Challenge is doable in F27. Never say never, we had 140 lbs person positioned and launched 800 lbs boat singlehandedly before, however, I think F27 is overkill. Besides, it is too shallow in many places for the boat. And again, how on earth are you expecting to paddle, row, propel it into checkpoints?
Can you enter Chokoloskee Bay? It is 5 miles of twisty narrow channel in mangroves. Can you enter Flamingo Marina? Sure, you can sail around Florida Bay, it will add only 40-50 miles to the trip :), but it is still necessary to get into Flamingo, inside of Marina.

Even it is all possible, and I personally believe that anything is possible, however time lost waiting for the right tide, current and wind will be much greater than time you can gain sailing a fast boat. Those pesky kayakers can maintain 5 knots 18 hours a day and I'm not even talking about Randy with his trimaran or Lumpy and Bumpy with their Tornado.

No, it is better to use something smaller. About any beach catamaran with capable 2-up crew can make it. It has been done on Tornado, Nacra 20, G-cat 6.0, Hobie 16, Hobie 18.

Singlehandedly it is much more difficult, in my opinion, however I have done it on old wooden A-class and my weird inflatable catamaran has been around entire Florida, all 1200 miles.
I wouldn't mind to take F16 on the course, if I had the money to trash expensive boat smile
Hobie Wave will make it, my inflatable is not faster.
In 2009 there was a guy who took H14 all way up to Flamingo. He dropped out there, some 30 miles from the finish, having another 3 days until deadline, I guess he was spent and it is hard to see kayakers flying by...
Anyway it is fun. I don't think that doing it in F27 will be fun, though.