Back to the original question....both tongue weights are important...you need the 1420 calculated without WD to show you what % of total weight of the trailer is on the tongue, and the 1080 with WD shows you how much weight the trailer adds to the truck going down the road.
I wouldn't worry about being slightly over GVWR if you are under GAWRs and most importantly tire ratings. Be conscious about adding more weight though...
Regarding GVWR, it's not all about capacity. Every OEM design is a compromise of capacity, efficiency and durability. The axles are rated to carry those loads, but the mfr is recommending that total vehicle weight be limited to less for other reasons, likely durability, ride comfort, etc. If you load past GVWR you will likely need accelerated service intervals and may experience faster component wear.
If the mfr allowed a higher GVWR and then recommended a more aggressive maintenance schedule to compensate, you would think the cost of ownership is too high. If the mfr recommended a higher GVWR and didn't increase the maintenance schedule, you may experience frequent repairs and perceive the dependability of the vehicle to be too low.
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Jimlin is correct on axle weights, the GVWR is recommended by the mfr for reasons they don't disclose...the important thing is to be aware of your weights and plan accordingly.
