Hi Ken,
Welcome to the Heartland Owners Forum and hopefully to the family. We have a great bunch of people here with lots of information and all willing to share their knowledge when needed.
I am not sure, but think Heartland gets all their frames from Lippert. As to problems with them, I don't remember any one posting about frames except on some of the older models and they were not toy haulers. If there were any, I think this is the first place folks go to and post their complaint.
Enjoy the forum.
Jim M