I WOULD "worry about it" since the rear tires are carrying a lot more weight. With ST tires he may be over the rear tires ratings.
The issue at question was on leveling. It was not on weight friend.
I would hope the tire weight rating is a given, when it comes to having the correct tires.
A standard 4 ply tire compared to the XL 10 ply tire will not in most circumstances make the trailer level, as what was the original main concern that was posted.
I understand what your point is, and also somewhat agree but, by looking at the pics given, this combo in my opinion does not fit the bill. As the two may not be exactly level, they are not that bad off as to where I believe it would be a concern. If that trailer's nose was drastically lifted and obviously putting more weight to the rear, then okay. I believe in his situation, he will be fine to ride safely and smoothly down the road.
Axles have been flipped.....maybe I need to go to a shorter tire on my truck.....
As long as it feels good pulling, I wouldn't worry about it anymore. It's mainly because your truck is lifted or just the trucks ride height.
Just because everything isn't perfectly level, doesn't mean it isn't safe going down the highway.