You put some time in that. ED vs Hemi Is mostly about the cooling system. ED will fail acceleration up a grade test due to derate before the Hemi. The fact that the Hemi weighs 80 pounds more than our ED is mostly offset by our 6950 GVWR versus 6900.
My particular VIN Quad cab Big Horn 3.92 Has a max tow of 8800 GCVWR 14,500.
What is not safe for ED above it’s cvwr but below max Cvwr for the 4th gen is the acceleration test fail via cooling system/ECM derate. Otherwise with aftermarket turbo brake software it’s actually more capable to control descent speed & keeping brakes cool for stopping. For our purposes cooling can be kept in check by limiting sustained rpm to 3K or less. But you can’t do that for j2807.
I have towed cvw of 15,800 over 6 percent grades on a 1,000 mile trip. Even with ideal weight distribution etc the 1/2 ton platform is pretty much tapped out at 16k. Axles receiver etc etc and in a real world most people won’t get their without somewhat grossly exceeding something simply for the fact that they don’t know the importance & value in setting WDH & loading to meet specs via adjustments according to CAT scale results.