A dump trailer is just about the handiest thing for a small tree company. I have a 6x12 with 6k axles under it.
I built a box so I could use it as a chip box.
Also put the tool box on the front which is VERY handy. Had to relocate the battery to under the bed and get a front crank jack.
The ASV RC30 still fits in even with the box on:
It will pretty much haul whatever I can fit in it: (and dump it no problem.)
I have since had it modified so that the gate is hinged to the sides and will swing open with great ease. I use to have to take the whole gate off to dump as it was either a spreader gate or a pickup type gate. (Worthless.)
A few things I wish mine did:
hold more - if I could do it again, I'd get at least a 8x14
dump higher - mine only dumps to about 27°
heavier axles - I'd get at least 7k axles if not 8k
brakes on both axles - it brakes fine but I'd rather it have brakes on both instead of just one.
Look around. There are plenty of companies that make them with the drop sides.
I think there's even one in the trading post here for sale with the drop sides.
Edit: just realized that last picture wasn't mine. It was a rental that I got right before I bought mine but it was about the same as mine and it shows how you can load them. That oak ain't light!