I wouldn't bother trying to fix. Just get these. A ton of us my cycling community all wear these for winter fat biking.
Front panel is windblock. Back side is breathable. Just pay attention to the sizing. I'm a 32 waist and 32 inseam. XL fits me. L is a little snugger.
https://www.amazon.com/4ucycling-Fle...-1-spons&psc=1
I have 3 pair of them. They haven't failed in any way yet and work aweseme during the cold months.