If you fixate on cargo capacity as the limiting factor, then yes, you likely will not be able to ever tow a 14,400lb 5er.
You have to decide for yourself how much weight/risk you put on exceeding cargo capacity vs rear axle weight.
I have a 1 ton Ram diesel. Cargo capacity is 3600(ish) if I recall. RGAWR is 7000lbs. I am currently towing a 5er that loaded, weights 13,500(ish I think,. going off memory). Pin weight is 3060(again memory). Loaded up, ready to camp, I exceed my cargo capacity by 20 lbs (so, maybe a couple buckets of chicken, and some ribs too probably), but am about 400 under my RGAWR. I have no issues with this, although there are some on here that will tell you (a) your truck will self destruct as soon as you put a pound over cargo capacity in it and/or (b) by exceeding payload by a pound you are going to put everyone, including all the leaders in the free world, in jeopardy, the minute you pull out of the driveway.
I subscribe the the RGAWR crowd, but you have to make your own decision based on a reasonable evaluation of the facts and your judgement.
Mike
