The length isn't such a big deal in my experience. Weight, speed and towing equipment are the important factors, along with great tires and shocks.
Make sure the boat and trailer combination aren't heavier than the rated towing capacity. Make sure you have really good, firm shocks that keep the vehicle in good control. Make sure you use a weight-distributing hitch -- it transfers some of the weight to the front tires for better distribution. Air up the tires to closer to the maximum listed on the sidewall; stay a few PSI short of maximum, though, since they'll gain some pressure as the tire temperature goes up.
Last but not least, keep your speed DOWN and enjoy the scenery!!
Cape Canaveral, Florida
2005 Jeep Grand Cherokee Laredo 4.7L
2005 Dodge Durango SLT 4.7L