We've hauled heavy. Just keep in mind, once you get above the 80% of stickered capacity, you have to be extra vigilant in a number of areas.
Things we've done to help over the years.
1. Heavier tow vehicle tires with stiffer sidewalls and higher pressure
2. Sway bars, heavier springs on tow vehicle
3. Definitely Weight Distribution Hitch (WDH) and Anti-sway bar/control
4. Slower speeds
5. Make sure the brakes on the trailer are in EXTRA GOOD condition, you'll need them with that weight
6. Larger transmission cooler
7. Transmission and turbo temp gauges
8. Take your time and enjoy the ride!
Not all of these are needed in every situation, but can give you some ideas.
IMHO, the max tow capacities are for stock vehicles and casual towing.
Heavy towing does put extra strain and wear on your tow vehicle, so follow the "Extreme Duty/Service" intervals for fluids and maintenance.
Have fun and welcome to the forum :)