Bert should take a lesson from the bumble bees. Aerodynamically, they can't fly 'cause some "experts" said the 'wing loading' was too great. Fortunately, the bees never read that dissertation so they fly anyhow.
I spent several months driving trucks at Bosch Automotive Proving Grounds at New Carlisle, IN. We ran most vehicles aroung the durability test track with about a 40% overload. It was called "Accellerated mileage accumulation." The track was 2.5 miles around and I drove around 100 miles a night on it. 100 miles on that track was the equivalent of 10,000 miles in real life. I'd not worry about being being 15 or 20% over what the sticker says on ANY diesel 3/4 or 1 ton.
http://www.bosch.de/start/media/news...ng_grounds.wmv