I can't speak for the Wilson trailer but we have a 20' Doonan we pull behind our Mack grain truck that would be pretty similar. Works well except for how low the hopper is to the ground...makes it interesting pulling over the swing hopper auger if the location is a little uneven. it will easily hold 30000 lbs of beans or corn. Routinely get 35,000 lbs of corn and no more than 30,000 lbs of beans on a load...trailer is rated at 40,000 and weights about 6800. 

We load it full most often than not so the truck doesn't have to be overloaded and still get 950-1100 bushels per load from field to binsite.

Our truck really needs a bigger engine to run like this in our hills but it handles the weight just fine...slower than a big block but we get home every load.