Hi Wayno,
Welcome to the Heartland Owners Forum and Family. We have a great bunch of people here with lots of information and all willing to share their knowledge if needed.
I never had anything put on the windows of my Bighorn,,, but thought about it...just never did it. I know a place in Corpus, and I'm sure there are others that put the tint on that has about a 50% heat blockage. I did have it on my PU and it seems to work.
Where did you purchase your North Trail? Local I hope so that you can get good service from Ben and his crew at ExploreUSA.
Enjoy the forum.
Jim M