Thanks for posting this. I knew my install didn't look quite right. I found a good video. Right at the 5 minute mark she shows that you need to tuck the back of the Sunrider behind the door frame. Quick fix by taking out 3 screws on each side if you missed it the first time.
Go smaller if you can, unless there is something you really like about this particular trailer. That said, for 50 miles unless you are on really tight roads you should be fine. Take your time, make wide turns. Also, for anything over 3000 lbs you will need to install a brake controller.
I live in Lansdale. Picked up my Black Overland on 8/1 from Bergey's in Souderton. Bought off the lot, a few points off of MSRP (as advertised), and they treated me fair on the trade-in. No nonsense and a pleasure to deal with. Ask for Julie.