I had terrible heat in the front cap. Fried some electronic equipment. I put a thermometer up there on a 98 degree day and registered 131 degrees.
So, here's how I fixed it... I removed the over dashboard cabinets, packed in a bunch of pink fiberglass insulation and put the cabinets back. This totally fixed it. The upper cabinets are the same temp and the interior of the coach.
By the way, on my RV I found the heat source. It wasn't the front cap or the roof. It was the 5" wide black stripe at the top of the windshield. That black strip wa 140 degrees in direct sun.
I would guess, but did not try it, that if you put a white vinyl stripe on the front of the windshield right over the black stripe (which is on the back of the windshield) that you're problem would be solved.
Here's my insulation fix:
2017 Winnebago Adventurer 37F
2016 Lincoln MKX Toad