lots of good advice here. also imho, i would suggest that you not bother showing your young dog the short gun at all. come out of the holding blind and show the dog the long gun only. the dog will usually have no trouble if you ease back a little pulling or if you ease forward a little pushing to see a short gun after they watch the long bird down.
blake, i watched a small crew of my subcontractors pour and finish 300 yards of concrete one day recently. they made it look so easy i told my mom i wouldn't mind doing her 3 yard patio and walk myself. it almost killed me. the competitors in that central arkansas derby you went to see were made up of many time nat open and nat am qualifiers, a nat open winner, some guys who have made multiple fc afc dogs, some of the south's top young dog pros and very respected amatuer handlers/trainers. they make it look easy at the trial. their dogs make it look easy at the trial.
you have a nice dog and can likely be competitive but you still gotta do the hard work all those guys who made it look easy already did. remember, you are looking for small, almost imperceptable, incremental gains in performance daily. focus on the four derbies you want to run next spring. this is like timber hunting in bayou meto, to quote my buddy blake, "if you don't know where the holes are you won't be successful and will just make it a long day for everyone else."