I think the Titan would do well towing a 22'.. One thing too keep in mind though, fuel mileage, i hear the Titan only gets approximately 13mpg, where as a F-250 PowerStroke can get almost 20mpg during daily driving.. My freinds 2001 f250 7.3litre is getting 21.5, and its a 4x4 w/33's on it.. Granted he has done some modifications.. The Titan is a very nice truck, but for towing it would be hard too beat a turbo diesel.. You may also want too check out NissanFrontier.net, there is a section for the Titan.. BTW, i drive a 2003 Frontier and am pleased w/it..
Hope this helps you out,
Rick
PS.. The new F-250 PowerStokes have a 6.0liter FWIW