The one I built was twin axles, though I would have stuck three under it, to lessen the load on the tires, but the buyer only wanted two... so two it was. He replaced the H rated tires as they went out, with F and ended up having a bunch of trouble with tires. He brought it by for me to see if I could figure out "why" he was having so many blowouts and I took one look at the tires on it and made a call. He went back to a tire rated to hold the weight and quit having problems. (or at least I never heard from him again)
I have an "Ugly dump trailer" that I built from a 45 foot boat trailer. Cut it down to about 27 ft, with a 20 ft flatbed, the rear 12 foot dumps. Had I left it the original length, it would have put the 33 ft to shame. At the time, I didn't have a gooseneck capable truck and needed a dump trailer to haul behind my JDeere, or if needed, to haul my JDeere. So, fired up the torch, dragged out the leads, and went to work.
Oh, by the way, my 33 ft trailer was a deckover, so the fenders didn't get in the way of the load or opening the doors on the vans as they were loaded and the drivers needed to get out (without banging up the doors on those fenders.
David from jax