Well I owned one for 19 years. Great machine. Are you talking about towing around a cart with weight in it or just that you are a big guy and don't want to over due it. Well I am about 240 and many times I pulled around a cart with dirt or rock in it. Never bent the axle, I sometime worried about it as the axle doesn't appear real big, but it did the job. Again, loved that mower and wish I hadn't sold it to a buddy, I tried to buy it back from him but he said no way, the best deal he ever made!
Hahaha. I forgot about the front end coming off the ground. Ok, scratch that idea.If your going be putting that much weight on the tongue, You might want to make sure you get some wheelie bars on that hot rod ! Maybe some weights on the front. It could be awfully hard on the trans. trying to pull that much weight over the yard and having the tires sinking it to the ground.
Good luck if ya' do and let us know how it works out .
Hahaha. I forgot about the front end coming off the ground. Ok, scratch that idea.
By the time it is all said and done I would use the 3520 to transport the dirt where you need it if you can. Probably faster and easier on you too.