I have a 2005 Nissan Titan 4x4 kingcab with the big tow package. I want to purchase a 16 to 18 foot 2 horse gooseneck (aluminum)with living quarters. My Titan is rated to 9500 lbs. The trailers I have been researching are running between 5000 to 5800 lbs. empty weight. I will be loading 2 1200 lb. horses.
Will I be ok towing that with what I have?
Any advice on gooseneck hitches or anything else that would help?

I've towed several trailers with Titans and they do well. The factory tow package has a lower axle ratio. Not low compared to American trucks. But with horses I'd stay around 8000#'s loaded. B&W made the first gooseneck ball hitch for the Titan back in 2004.