Kayaks:
Lazy Dog Adventure Club,
Will deliver and pick up Kayaks to race Start/Finish
http://www.lazydogadventure.com/
Toll Free
1-866-293-9550

Blue Planet Kayak
Tours and Rentals
305-294-8087 

http://www.blue-planet-kayak.com/rental.html

Boat Rentals of Key West
http://www.boatrentalsofkeywest.com/ourboats.htm
Pontoons and 4 stroke motors (Less fumes)
888-288-8395
I have not gotten a response yet about 6AM Start time 
*******************

Paradise Boat rentals
Craig 305-304-4220
Has worked with Swim team before 6 AM no Problem
16' $289 and 26' $389
********************

Sunset Watersports,
305-294-1500,  http://www.sunsetwatersportskeywest.com/key-west-boat-rentals.html

They will rent a boat for the day starting at 5:30 AM for a $50 extra fee.

17' $325 Bimini top
20' $350 T Top
22' $400 T top
Deck boat $450 Bimini top