Funny how we differ this side of the water. The majority of pros here and in England shoot O&U.Thats why I was wondering was it an American thing.
I shot at county level here(same as your state level)and my friend shoots international. He has a Perazzi and keeps 2 sets of barrels, but as you said these are sporting traps.
Just for getting the feel of a gun, get a 2ft piece of cardboard and draw a target in the centre.
Place it roughly 20ft from you. Mount the gun as fast as you can and fire at the centre of the target.It will give you a rough idea if you are firing left or right, to high or low.
It is not that hard a job to get the stock of the gun bent to suit your shooting and should not cost that much.