I got the Thule rack for the Jazz from:
http://www.car-roofracks.co.uk/cgi-b...racks_bars.cgi
it fits fine-so far we have the Hull-A-Ports (J Racks) up and driving at high speeds creates a lot of wind resistance and we haven't even tried the 2 kayaks yet. So I'm not sure driving at high speeds long distance will be good. I have no idea on weight but Honda Japan makes a roof rack adn kayak attachment for the Japan Fit so I am assuming the US Fit can accomodate the weight of these.