15% tongue weight seems high. Mfr suggests 10% minimum and most folks seem to prefer 11-12%. My trailer is about the same weight and I have a 1/10K EQ hitch with 925-975 lbs. tongue wt. by the Sherline scale depending on what we pack. Works fine.
I discovered my "sockets" (the female square tube receivers on the truck part of the hitch) were cracked at the corners. I discovered this 3 days before we left for a 3,600 mile run to Colorado. I called Progressive Industries and sent pictures. They over-nighted new sockets for free, but actually said cracks in that area were not unusual. Then he asked me to go check the length of the shank on my hitch ball and see if it extended below the flat plate.
Sure enough the dealer had installed a ball with a shank too long. In a hard turn, the sockets hit the shank and can't rotate any further, but while the truck/trailer are still rotating further. He said this is what caused my cracks. They see it a lot because the shank length they require is a bit hard to find.
A structural failure on a hitch this heavy would really be alarming. Suggest you see if the shank of your hitch ball extends below the surface of the top plate where the sockets rotate.