Since the axle ratings have went up by 500lb, perhaps GVWR will go up by 1000lb to 6000lb?
Yes the total of the axle capacities of the 19' is 5000 lb (2 at 2500 lb each); for the 21' it is planned to be 6000 lb (2 at 3000 lb each). That's a 1000 pound increase.
The Gross Vehicle Weight Rating (GVWR) of the 19' is 4000 pounds, so a 1000 pounds more would be 5000 pounds, not 6000 pounds.
Since the total of the two axle capacities is 6000 pounds, why not set the GVWR up at the same value? They're Dexter Torflex axles, and like other suspensions of this type they do not share load equally over bumps, so the total trailer weight must be kept below the total of the axle capacities. Escape appropriately limits the GVWR as Dexter Axle directs.