I have a 5' by 8' and a 6' by 12' dumping trailers.
I notice the 6x12 has more tongue weight than the 5x8, I really need to pay attention to how I load the weight on the bigger trailer.
My 5x8 is a 6000lb single axle trailer, empty weight is 1450. I have high enough sides to put in a cord of wood, wet or dry. I have loaded it with upwards of 3 yards of topsoil before, hauled it fine and dumped it fine. That being said, i was using on 06' v-8 silverado. Plus side with this trailer, a cam, is that it is essentially the same as the 3000lb one with no brakes. Mine weighs probably less than 100lbs more and has breaks. You can tow it fine with your pickup; if you are worried about how the truck sits, put on an extra stack of leaf springs. I put on a second stack from jc whitney, about $300 and a saturday morning with a friend took care of it. Now when I tow my 6x12 with 2 full cord of wood, the truck looks like it is sitting with no weight in the trailer.
I have both dump trailers and my dump truck, once you go dumping, you won't want to go back to the old fashion way, well worth the extra money.