I don’t know how to tell which manufacture. I have a 2012 Lake of the Woods model. It has been good. Mine has rectangle tubing around the perimeter. I think the ones that had the worst problems were the earlier years with the angle iron frames.
The frame problems aren’t caused by the fabrication.
As Beardly stated it’s in the design.
Angle iron frames will twist and flex more than a square tube.
A 2” square tube 1/8” thick would be the equivalent of a 4” by 1/4” angle iron.
it sounds like this is a better frame then in the past. after the 4th I was going to put it up on blocks and service the pivots and do something with the paint on the frame.