When we bought our trailer a couple of months ago, the guy doing the PDI did a nice job. Two things that chapped me though was after the PDI, he took me into their store and proceeded to try to sell me a bunch of crap. Secondly, the dealership was to set up the hitch. The guy doing the hitch was trying his best but the manager of the dealership was more interested in getting me out of the lot than getting me away with my hitch safely installed. And, the entire time I was there, which was about three hours, the manager never spoke to me at all.
About the hitch, if I had not have read up on this particular hitch and had a working knowledge of WDH's, I would have had disastrous results. I made them get it right or I would not leave.
At this point, if it were me, I would set the trailer up, get my owner's manual and all the other manuals that came with the trailer and have a self instructed school.
Good luck!