A nice feather of the swing up rear ramps is most provide support to the back of the trailer and take the extreme weight off the tow vehicle... I have seen rear wheels of trucks lifter clear off the ground when the rear deck of the trailer was not supported... you can imagine the disaster waiting to happen if you happened to be on an incline...
Some of the guys here are going with dump trailers for their track bobcats... they find them more versatile for hauling materials and transport to and from the job.
The preferred set up seems to by two 6000# axles giving a 12k trailer derated to 9,990 pounds for licensing.