Seems silly to insist on putting the boat on top. Much more logical would be to make the truck into a motorhome and pull the boat trailer...if you want more storage the front of the boat trailer could be outfitted with storage boxes.
Looking at the toys he has, the Dodge never had any issue pulling the toys...just putting the boat on the roof was a problem.
Also, while they might not give him a hassle on dirt roads in the outback, I suspect he will be overweight if he tries to pull 66k lbs... Of course, if it's about chest pounding, I saw a stock toyota tacoma tow the space shuttle, so 66k lb is nothing.