interesting topic. In a perfect world, I would also say look at 7K. The world of trailer possibilities seem to open up at 7K (2 3500 axles) and 16-20 length. BUT, in the real world, we all have to live within our limitations. I may have missed it, but what is the towing capacity of your Frontier? It is also true - if you buy a 14, you will wish you had a 16' and if you buy an 18'', there will be times you want a 20'. But, STAY within the capabilities of your tow vehicle. Filling the fuel tank may put you over the Gross Vehicle Weight. I have had many people tell me that it is not necessary to worry too much about weight limits - you will never be stopped by the Highway Patrol and you don't need to scale (not commercial). But, my trailer is a 14K Doolittle EZTilt and weights 3700. My tractor with loader and box blade weighs 6200. I sometimes stop at a CAT scale to see that the weight is correct. And my concern is NOT about being stopped for overweight. It is if there is an accident, no matter who is at fault, everyone including the HP and you insurance will be concerned about how heavy you were when it happened. That is why my first consideration is the tow vehicle. You also may want to concentrate on EZlube axles and other features such as tie down locations (stake pocket and rub rail) and off set front jack. Best wishes, Larry